s390: add support for IBM z14 machines

Add detection for machine type 0x3906 and set the ELF platform name
to z14. Add the miscellaneous-instruction-extension 2 facility to
the list of facilities for z14.

And allow to generate code that only runs on a z14 machine.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/kernel/setup.c

@@ -818,6 +818,9 @@ static int __init setup_hwcaps(void)
 	case 0x2965:
 		strcpy(elf_platform, "z13");
 		break;
+	case 0x3906:
+		strcpy(elf_platform, "z14");
+		break;
 	}
 
 	/*