arm64: Remove TCR_CACHE_ATTRS and TCR_SMP_ATTRS

These are only used in one place so expand them there.

While here always set TCR_SH0_IS and TCR_SH1_IS. There is no advantage
to not set them in a UP kernel.

Reviewed by: alc, kib, markj
Sponsored by: Arm Ltd
Differential Revision: https://reviews.freebsd.org/D46393