memory: Log access direction for invalid accesses

In memory_region_access_valid() invalid accesses are logged to help
debugging but the log message does not say if it was a read or write.
Log that too to better identify the access causing the problem.

Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: BALATON Zoltan <balaton@eik.bme.hu>
Message-Id: <20211011173616.F1DE0756022@zero.eik.bme.hu>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>