s390/time: clock comparator revalidation

Always use the S390_lowcore.clock_comparator field to revalidate
the clock comparator CPU register after a machine check. This avoids
an unnecssary external interrupt after a machine check if no timer
is pending.

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

arch/s390/kernel/nmi.c

@@ -214,10 +214,7 @@ static int notrace s390_revalidate_registers(struct mci *mci)
 			: "0", "cc");
 #endif
 	/* Revalidate clock comparator register */
-	if (S390_lowcore.clock_comparator == -1)
-		set_clock_comparator(S390_lowcore.mcck_clock);
-	else
-		set_clock_comparator(S390_lowcore.clock_comparator);
+	set_clock_comparator(S390_lowcore.clock_comparator);
 	/* Check if old PSW is valid */
 	if (!mci->wp)
 		/*