ac/surface: adapt surf_size when modifying surf_pitch
Otherwise we might get VM_L2_PROTECTION_FAULT_STATUS errors. Fixes: 8275dc1e ("ac/surface: fix epitch when modifying surf_pitch") Reviewed-by:Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl> Reviewed-by:
Marek Olšák <marek.olsak@amd.com> Part-of: <mesa/mesa!5841> (cherry picked from commit 87ecfdfb)