Refactor block_rd_txfm()
Refactor block_rd_txfm()

Merge two identical if branches.

Change-Id: Ie012ba9c116a30ef6fa2e7868c7a4ba886b99bc6

ShiftMediaProject/libvpx,ShiftMediaProject/libvpx,webmproject/libvpx,webmproject/libvpx,ShiftMediaProject/libvpx,ShiftMediaProject/libvpx,webmproject/libvpx,ShiftMediaProject/libvpx,webmproject/libvpx,webmproject/libvpx,webmproject/libvpx