eg/compute: Drop reference to kernel_param bo in destructor

CC: <mesa-stable@lists.freedesktop.org>
Signed-off-by: Jan Vesely <jan.vesely@rutgers.edu>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
(cherry picked from commit a9e4be9212)

src/gallium/drivers/r600/evergreen_compute.c

@@ -462,6 +462,7 @@ static void evergreen_delete_compute_state(struct pipe_context *ctx, void *state
 #ifdef HAVE_OPENCL
 		radeon_shader_binary_clean(&shader->binary);
 		pipe_resource_reference(&shader->code_bo, NULL);
+		pipe_resource_reference(&shader->kernel_param, NULL);
 #endif
 		r600_destroy_shader(&shader->bc);
 	}