Prevent OOB read in rw_mfc_writeBlock

Bug: 140768035
Test: read/write mifare tag
Change-Id: I46908c8a086e5998aa67a0b6e0f6b4ef67f7f1ae
(cherry picked from commit b19ea93a06a67060acfa4bf0d5938fcd27a6d007)
1 file changed