treewide: capitalize 'BIOS'

Also replace 'BIOS' by coreboot when the image is 'coreboot.rom'.

Change-Id: I8303b7baa9671f19a036a59775026ffd63c85273
Signed-off-by: Elyes HAOUAS <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/38932
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>

src/soc/intel/skylake/lockdown.c

@@ -22,7 +22,7 @@
 
 static void lpc_lockdown_config(int chipset_lockdown)
 {
-	/* Set Bios Interface Lock, Bios Lock */
+	/* Set BIOS Interface Lock, BIOS Lock */
 	if (chipset_lockdown == CHIPSET_LOCKDOWN_COREBOOT) {
 		lpc_set_bios_interface_lock_down();
 		lpc_set_lock_enable();