MFC r302523,r302528:

r302523:
Add clk_get_by_ofw_node_index, which is like clk_get_by_ofw_index but
operates on a specific OF node instead of the pass in device's OF node.
r302528:
EXTRES: Add OF node as argument to all <foo>_get_by_ofw_<bar>() functions.
In some cases, the driver must handle given properties located in specific
OF subnode. Instead of creating duplicate set of function, add 'node' as
argument to existing functions, defaulting it to device OF node.

Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Use OF_prop_free instead of direct call to free(9)

Reviewed by: mmel@

Fix support for fixed factor clocks.
- Use a different device description for fixed and fixed factor clocks.
- Fix a bug where the "clock-div" property was stored in the "mult" field
of the clock definition.
- Get the fixed factor parent clock by index instead of by name, as a
clock-names property is not required to be present here.

Reviewed by: mmel, adrian (mentor)
Approved by: adrian (mentor)
Differential Revision: https://reviews.freebsd.org/D5703

CLK: Add enumerator for 'clocks' OFW node. Add bus device bindings
for clk_fixed class.

CLK: Remove forgotten mutex from clk_fixed class.

Add clock framework, a first part of new 'extended resources' family of
support frameworks(i.e. reset/regulators/phy/tsensors/fuses...).

The clock framework significantly simplifies handling of complex clock
structures found in modern SoCs. It provides the unified consumers
interface, holds and manages actual clock topology, frequency and gating.

It's tested on three different ARM boards (Nvidia Tegra TK1, Inforce 6410 and
Odroid XU2) and on one MIPS board (Creator Ci20) by kan@.

The framework is still far from perfect and probably doesn't have stable
interface yet, but we want to start testing it on more real boards and
different architectures.

Reviewed by: ian, kan (earlier version)