MFC r327367:

Make kernel option KERNVIRTADDR optional, remove it from std.<platform>
files that can use the default value.

It used to be required that the low-order bits of KERNVIRTADDR matched
the low-order bits of the physical load address for all arm platforms.
That hasn't been a requirement for armv6 platforms since FreeBSD 10.
There is no longer any relationship between load addr and KERNVIRTADDR
except that both must be aligned to a 2 MiB boundary.

This change makes the default KERNVIRTADDR value 0xc0000000, and removes the
options from all the platforms that can use the default value. The default
is now defined in vmparam.h, and that file is now included in a few new
places that reference KERNVIRTADDR, since it may not come in via the
forced-include of opt_global.h on the compile command line.

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

Move ARM_L2_PIPT option to std.armv6 for all armv6 platforms.
Only L2 PIPT cache is supported for __ARM_ARCH >= 6.

In fact, this is just a pure proclamation as this option is used
only in armv4 specific files now.

Makeoption ARM_LITLE_ENDIAN does nothing. Remove it since it isn't
consistently used. It was a carry over from NetBSD that FreeBSD
doesn't use.

Stop setting {KERN,}PHYSADDR on armv6, it's unneeded.

Sponsored by: ABT Systems Ltd

Remove -Wa,-march=armv7a from arm kernel configs, it makes clang 3.5 sad
and apparently isn't needed now that we're using the integrated assembler.

Add -march=armv7a to the kernel compile for all ARM systems which are v7a.

Submitted by: Michal Meloun <meloun@miracle.cz>

Add initial support for Altera SOCFPGA (heterogeneous ARM/FPGA) SoC family.
Include board configuration for Terasic SoCKit (Altera Cyclone V).

Sponsored by: DARPA, AFRL