arm64: Disable PAC when booting on a Windows Dev Kit 2023

It appears that PAC registers are configured to trap upon access, but
since the kernel starts in EL1 on this platform it has no ability to
inspect or modify this configuration. Simply disable PAC on this
platform for now, since the kernel otherwise hangs during boot.

PR: 270472
Reviewed by: andrew, emaste
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D39748