arch: arm64: program TG[1] in mmu init

In performing a double check of Zephyr arm64 MMU config
against edk2, a different in the programming of the
Translation Control Register (TCR) was found.  TCR.TG[1]
should be set to address Cortex-A57 erratum 822227:

"Using unsupported 16K translation granules might cause
Cortex-A57 to incorrectly trigger a domain fault"

Signed-off-by: Eugene Cohen <quic_egmc@quicinc.com>