Restore the use of "vpxor" instructions

previously "vpxor" instruction was mistakenly replaced by "aomor" as
port of vpx->aom renaming change. This commit revert that change for
where vpxor instruction should be used in asm code.

Change-Id: I411d95f5d8fa5ed380c8b0d6021118b6c1e9bfb9
3 files changed