Fix the TCR_TG0 values

They are in a different order to the TCR_TG1 values but appear to have
been copied incorrectly.

While here use TCR_TG0_4K in locore.S to make it explicit the userspace
page size is 4K.

Sponsored by: The FreeBSD Foundation

(cherry picked from commit f62e099ed51bf15ebafa20a044e106480547a0ad)