KVM: selftests: aarch64: Do not default to dirty PTE pages on all S1PTWs

Only Stage1 Page table walks (S1PTW) trying to write into a PTE should
result in the PTE page being dirty in the log.  However, the dirty log
tests in page_fault_test default to treat all S1PTW accesses as writes.
Fix the relevant tests by asserting dirty pages only for S1PTW writes,
which in these tests only applies to when Hardware management of the Access
Flag is enabled.

Signed-off-by: Ricardo Koller <ricarkol@google.com>
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20230127214353.245671-3-ricarkol@google.com