isl: Mark A4B4G4R4_UNORM as supported on gen8
isl: Mark A4B4G4R4_UNORM as supported on gen8

Reviewed-by: Kenneth Graunke <bd2562f754ec92342f93f61c25d731e290a2ffa8@whitecape.org>
Cc: "13.0" <4a7dc73e2393621c9290144a497188a9d4f7d87e@lists.freedesktop.org>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler