Extend struct todr_chip_handle with a todr_quality member. This allows us
to assign a quality to RTC implementation and pick the "best" RTC if a
system has multiple RTCs (or multiple interfaces to an RTC). This allows
us to prefer a battery-backed I2C RTC over an RTC that is part of the SoC
which is only running of the SoC is powered. It also allows us to
work around issues with firmware RTC interfaces that may lie to us or
even crash the system.

This change makes sure the todr_quality member of the struct is always
initialized. In most cases the quality will be set to zero; further
adjustments of the quality for specific subsystems/architectures will follow.

ok cheloha@, patrick@

Remove unused function pointers from `todr_handle'.

from miod@

Add function for attaching RTC drivers, to reduce direct use
of todr_handle.

OK kettenis@

First pass at removing clauses 3 and 4 from NetBSD licenses.

Not sure what's more surprising: how long it took for NetBSD to
catch up to the rest of the BSDs (including UCB), or the amount of
code that NetBSD has claimed for itself without attributing to the
actual authors.

OK deraadt@

move clock_subr.c to a better place, and now it is always in the kernel
so that things can use it; tested on all architectures; ok kettenis

First round of __P removal in sys

branches: 1.2.4;
generic interface for time-of-day clock devices.
From NetBSD

branches: 1.1.12;
Code imported from NetBSD. -moj

Remove unused function pointers from `todr_handle'.

from miod@

Add function for attaching RTC drivers, to reduce direct use
of todr_handle.

OK kettenis@

First pass at removing clauses 3 and 4 from NetBSD licenses.

Not sure what's more surprising: how long it took for NetBSD to
catch up to the rest of the BSDs (including UCB), or the amount of
code that NetBSD has claimed for itself without attributing to the
actual authors.

OK deraadt@

move clock_subr.c to a better place, and now it is always in the kernel
so that things can use it; tested on all architectures; ok kettenis

First round of __P removal in sys

branches: 1.2.4;
generic interface for time-of-day clock devices.
From NetBSD

branches: 1.1.12;
Code imported from NetBSD. -moj

Add function for attaching RTC drivers, to reduce direct use
of todr_handle.

OK kettenis@

First pass at removing clauses 3 and 4 from NetBSD licenses.

Not sure what's more surprising: how long it took for NetBSD to
catch up to the rest of the BSDs (including UCB), or the amount of
code that NetBSD has claimed for itself without attributing to the
actual authors.

OK deraadt@

move clock_subr.c to a better place, and now it is always in the kernel
so that things can use it; tested on all architectures; ok kettenis

First round of __P removal in sys

branches: 1.2.4;
generic interface for time-of-day clock devices.
From NetBSD

branches: 1.1.12;
Code imported from NetBSD. -moj

First pass at removing clauses 3 and 4 from NetBSD licenses.

Not sure what's more surprising: how long it took for NetBSD to
catch up to the rest of the BSDs (including UCB), or the amount of
code that NetBSD has claimed for itself without attributing to the
actual authors.

OK deraadt@

move clock_subr.c to a better place, and now it is always in the kernel
so that things can use it; tested on all architectures; ok kettenis

First round of __P removal in sys

branches: 1.2.4;
generic interface for time-of-day clock devices.
From NetBSD

branches: 1.1.12;
Code imported from NetBSD. -moj