Revert "Simplify mask checking in loop filters"

Jingning saw bitstream change with this patch. It could be true
that (mask_16x16_0 & 1) is 1, but (mask_16x16_1 & 1) is 0 in some
edge cases.

This reverts commit 8f05e703.

Change-Id: I0a529435ce816a1e14653eb510d5090de276070a