anv: Move INTERFACE_DESCRIPTOR_DATA setup to the pipeline

There are a few dynamic bits, namely binding table and sampler addresses,
but most of it is static and really belongs in the pipeline.  It certainly
doesn't belong in flush_compute_descriptor_set.  We'll use the same state
merging trick we use for gen7 DEPTH_STENCIL.

Reviewed-by: Kristian H. Kristensen <hoegsberg@google.com>
Reviewed-by: Timothy Arceri <timothy.arceri@collabora.com>

src/intel/vulkan/anv_private.h

@@ -1414,6 +1414,8 @@ struct anv_pipeline {
    struct {
       uint32_t                                  wm_depth_stencil[4];
    } gen9;
+
+   uint32_t                                     interface_descriptor_data[8];
 };
 
 static inline bool