ANDROID: KVM: arm64: s2mpu: Allow reading MPTC entries

The state of the S2MPU does not need to be kept secret from the host as
it merely reflects the permissions that the host has and knows about.
To make debugging DMA issues easier, allow the host to query entries
from the MPTC cache. This involves writing the set and way IDs of the
query to the READ_MPTC register and then reading the MPTC entry
information from READ_MPTC_TAG_PPN/TAG_OTHERS/DATA. Modify the S2MPU
DABT handler to allow this register access pattern.

Bug: 190463801
Bug: 229793579
Signed-off-by: David Brazdil <dbrazdil@google.com>
Change-Id: I6bbcafa6b21c541774932c3b197d2888fd50202c