firmware: meson_sm: Mark chip struct as static const

No need to be a global struct.
Reviewed-by: Jerome Brunet <jbrunet@baylibre.com>
Signed-off-by: Carlo Caione <ccaione@baylibre.com>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>

drivers/firmware/meson/meson_sm.c

@@ -35,7 +35,7 @@ struct meson_sm_chip {
 	struct meson_sm_cmd cmd[];
 };
 
-struct meson_sm_chip gxbb_chip = {
+static const struct meson_sm_chip gxbb_chip = {
 	.shmem_size		= SZ_4K,
 	.cmd_shmem_in_base	= 0x82000020,
 	.cmd_shmem_out_base	= 0x82000021,