src/mainboard: Use 'const' to set pnp_devfn_t statically

Change-Id: I50ac6914fadc02491df2eccb437eada89fd12b82
Signed-off-by: Elyes HAOUAS <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/40272
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
diff --git a/src/mainboard/kontron/ktqm77/early_init.c b/src/mainboard/kontron/ktqm77/early_init.c
index 5651064..949eab2 100644
--- a/src/mainboard/kontron/ktqm77/early_init.c
+++ b/src/mainboard/kontron/ktqm77/early_init.c
@@ -35,7 +35,7 @@
 {
 	int lvds_3v = 0; /* 0 (5V) or 1 (3V3) */
 	int dis_bl_inv = 1; /* backlight inversion: 1 = disabled, 0 = enabled */
-	pnp_devfn_t dev = PNP_DEV(0x2e, 0x9);
+	const pnp_devfn_t dev = PNP_DEV(0x2e, 0x9);
 	pnp_enter_conf_state(dev);
 	pnp_write_config(dev, 0x29, 0x02); /* Pins 119, 120 are GPIO21, 20 */
 	pnp_write_config(dev, 0x30, 0x03); /* Enable GPIO2+3 */