libpayload: Add missing break statement

Change-Id: I073b9bd30f4f9b0cdf6c45c10e4549889342d5f3
Signed-off-by: Patrick Georgi <patrick@georgi-clan.de>
Found-by: Coverity Scan
Reviewed-on: http://review.coreboot.org/7970
Tested-by: build bot (Jenkins)
Reviewed-by: Martin Roth <gaumless@gmail.com>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>

payloads/libpayload/arch/x86/coreboot.c

@@ -270,6 +270,7 @@ static int cb_parse_header(void *addr, int len, struct sysinfo_t *info)
 #endif
 		case CB_TAG_MAINBOARD:
 			info->mainboard = (struct cb_mainboard *)ptr;
+			break;
 #ifdef CONFIG_LP_CHROMEOS
 		case CB_TAG_GPIO:
 			cb_parse_gpios(ptr, info);