MFC r350112, r350241, and r350242:

r350166:
arm64: Implement HWCAP

Add HWCAP support for arm64.
defines are the same as in Linux and a userland program can use
elf_aux_info to get the data.
We only save the common denominator for all cores in case the
big and little cluster have different support (this is known to
exists even if we don't support those SoCs in FreeBSD)

Differential Revision: https://reviews.freebsd.org/D17137

r350241:
Ensure the arm64 ID register fields are 64 bit types.

Previously only some of the ID register fields were 64 bit. To allow
for a script to generate these mark them all 64 bit. To allow for their
use in assembly we need to use the UINT64_C macro via a new UL macro
to stop the lines from being too long.

Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D20977

r350242:
As with r350241 use the new UL macro on the main register mask.

Sponsored by: DARPA, AFRL