freedreno: fix crash on smaller gpus and higher resolutions
Devices with smaller GMEM size need more tiles. On db410c at 2048x1152, glmark2 shadow needed ~330 tiles for fullscreen. Lets bump it up to 512. (Maybe with MRT you could end up needing more, but at that point things are probably going to be painfully slow.) Signed-off-by:Rob Clark <robdclark@gmail.com> (cherry picked from commit 7295428e)