zink: use only ZINK_BIND_DESCRIPTOR (Reviewed in !27976)
ZINK_BIND_RESOURCE_DESCRIPTOR and ZINK_BIND_SAMPLER_DESCRIPTOR are always used together, so that we can replace these two values with ZINK_BIND_DESCRIPTOR and use only one bit to represent the value. With that we can also remove the aliasing of ZINK_BIND_DESCRIPTOR with PIPE_BIND_CONST_BW.
The patch was reviewed in !27976