i965/surface_formats: Mark A4B4G4R4_UNORM as SKL+ only
i965/surface_formats: Mark A4B4G4R4_UNORM as SKL+ only

This is what is indicated by the bspec.

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler