Revert "Enable OMAP4 SGX workaround for OMAP3 too"

Since the new TI SGX DDK 1.12 has fixed support for RGBA8888,
the workaround can be reverted. This may help with CTS issues.

Bug: 14995811
This reverts commit 6e79cb81.

Change-Id: Id8160ebe577d7009d2dd5eb4501ec40356a4274d