[S390] avoid STCKF if running in ESA mode

In ESA mode STCKF is not defined even if the facility bit is enabled.
To prevent an illegal operation we must also check if we run a 64 bit kernel.
To make the check perform well add the STCKF bit to the machine flags.

Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/include/asm/timex.h

@@ -90,7 +90,7 @@ static inline unsigned long long get_clock_fast(void)
 {
 	unsigned long long clk;
 
-	if (test_facility(25))
+	if (MACHINE_HAS_STCKF)
 		asm volatile(".insn	s,0xb27c0000,%0" : "=Q" (clk) : : "cc");
 	else
 		clk = get_clock();