radv: Only enter the immutable samplers init loop when we have some.

Reviewed-by: Dave Airlie <airlied@redhat.com>
Reviewed-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>

src/amd/vulkan/radv_descriptor_set.h

@@ -68,6 +68,8 @@ struct radv_descriptor_set_layout {
    /* Number of dynamic offsets used by this descriptor set */
    uint16_t dynamic_offset_count;
 
+   bool has_immutable_samplers;
+
    /* Bindings in this descriptor set */
    struct radv_descriptor_set_binding_layout binding[0];
 };