cpu/x86/mtrr/xip_cache.c: Fix inconsistent message

Change-Id: Ic99e61632664f86cc12507f2ddffa364fdd79202
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/36585
Reviewed-by: Nico Huber <nico.h@gmx.de>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/cpu/x86/mtrr/xip_cache.c

@@ -63,7 +63,7 @@ void platform_prog_run(struct prog *prog)
 	if (cpu_info.x86 == 0xf) {
 		printk(BIOS_NOTICE,
 		       "PROG_RUN: CPU does not support caching ROM\n"
-		       "The next stage will run slowly\n");
+		       "The next stage will run slowly!\n");
 		return;
 	}