radv: fix border color swizzle for stencil-only format on GFX9+

Swizzle of 8-bit stencil format is defined as _x__ but the hw expects
BC_SWIZZLE_XYZW.

Fixes dEQP-VK.pipeline.monolithic.sampler.border_swizzle.*s8_uint*.

Cc: mesa-stable
Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/21482>
(cherry picked from commit 7b2086d741920ec302d0e8830242f4555948583b)
2 files changed