i965 and iris: Don't advertise Y-tiled modifiers for scanout buffers on Gfx8-
According to isl_gfx7.c:264, the display engine does not support Y tiled buffers prior to Skylake. But we exposed I915_FORMAT_MOD_Y_TILED even when querying for a list of modifiers with __DRI_IMAGE_USE_SCANOUT set, which we can't support. That led to crashes later when we tried to create such an image, and isl rightly denied it.
This duplicates a bit of code from ISL, but the isl_gfx6_filter_tiling function that we ought to use to filter things relies on surf_info, which we don't have at this stage. This is probably good enough.
Closes: #4815 (closed)
Edited by Kenneth Graunke