d3d12: Sets all SRV descriptors as data-static
As Mesa d3d12 is currently implemented, all resource data is static at the time a SRV or CBV is created. Therefore, it makes sense for all descriptors to use the DESCRIPTORS_STATIC_KEEPING_BUFFER_BOUNDS_CHECKS flag. Use of this flag broadens debug validation and allows some optimizations in the underlying driver. Part-of: <mesa/mesa!10871>