trusty:mmutest: Update run_x test to check and support ARM64 WXN.

WXN means the previous run_x test will fail since it has a writable
mapping.  Update the test to expect this, and also check WXN is
configured.

Bug: 328206729
Test: build.py --test com.android.wxntest
Change-Id: I23e52a69de9dff69dee2b080ff83b939b523c6b2
1 file changed