Alternative to !20686 (merged)
Nowadays, mesa/st is able to emulate alpha, luminance, and intensity formats. From GL and Vulkan standpoint, there's no need to support any of these formats in the driver anymore. I would remove all support, but the most popular of these formats are used in Nine and there's no emulation support in Nine yet. So, this patch removes support for all alpha/luminance/intensity formats except the subset used by nine: A8_UNORM, L8_UNORM, L8A8_UNORM.
Nine also uses L4A4_UNORM but that's not wired up yet.
I also don't really understand why people would use Nine on Mali hardware but I digress.
Cc @okias to confirm this is ok for Nine.