freedreno/a6xx: Fix partial z/s clears with sysmem
We have to set 8c01 to say "leave these channels alone" when clearing/storing just Z or S of z24s8. Fixes the bypass path for KHR-GLES3.packed_depth_stencil.verify_read_pixels.depth24_stencil8.
Cc: mesa-stable Fixes: #5592 (closed)
Edited by Emma Anholt