The codec name is defined in av1_dx_iface.c
This name needs to match kAV1Name in decode_test_driver.cc.
Otherwise the EndtoEndPSNRTest fails when built with --enable-ext-tile,
(because we need the IsAV1 function to return true.)

Change-Id: I05d5ea5b6fd4bbd49e8bcacd047fb81c27efb3b3