radv: simplify the logic in radv_set_descriptor_set()

Now that 'set' can't be NULL because the meta operations no
longer bind a NULL descriptor, the logic can be simplified
a little bit.

Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>

src/amd/vulkan/radv_cmd_buffer.c

@@ -528,10 +528,8 @@ void radv_set_descriptor_set(struct radv_cmd_buffer *cmd_buffer,
 		radv_get_descriptors_state(cmd_buffer, bind_point);
 
 	descriptors_state->sets[idx] = set;
-	if (set)
-		descriptors_state->valid |= (1u << idx);
-	else
-		descriptors_state->valid &= ~(1u << idx);
+
+	descriptors_state->valid |= (1u << idx); /* active descriptors */
 	descriptors_state->dirty |= (1u << idx);
 }