ac: fix PIPE_FORMAT_R11G11B10_FLOAT DST_SEL_W

ac: fix PIPE_FORMAT_R11G11B10_FLOAT DST_SEL_W

Previously, the W component would be incorrect for attributes using this
format when loaded in RADV's vertex shader prologs.

Fixes dEQP-VK.pipeline.fast_linked_library.vertex_input.*b10g11r11*missing_components*

Signed-off-by: Rhys Perry <pendingchaos02@gmail.com>
Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
Reviewed-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Fixes: 6a2ada93b49 ("ac: add ac_vtx_format_info")
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/23645>