radeon: Fill in the TXOFFSET field containing the tile bits in our relocs.

radeon: Fill in the TXOFFSET field containing the tile bits in our relocs.

The first arg to OUT_BATCH_RELOC is ignored, we actually wanted these
in the third arg.  They're always 0 so far, so it didn't matter.

v2: Reword commit message that I don't end up using the tile bits, but
    keep the commit as a cleanup anyway.

Reviewed-by: Marek Olšák <marek.olsak@amd.com> (v1)