s390: add support for IBM zBC12 machine

Just add the new model number where appropiate.

Cc: stable@vger.kernel.org # v3.10
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/kernel/setup.c

@@ -994,6 +994,7 @@ static void __init setup_hwcaps(void)
 		strcpy(elf_platform, "z196");
 		break;
 	case 0x2827:
+	case 0x2828:
 		strcpy(elf_platform, "zEC12");
 		break;
 	}