s390/cpum_cf_diag: use get_tod_clock_fast()

Use get_tod_clock_fast() instead of store_tod_clock(), since
store_tod_clock() can be very slow.
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

arch/s390/kernel/perf_cpum_cf_diag.c

@@ -119,7 +119,7 @@ static void cf_diag_trailer(struct cf_trailer_entry *te)
 		te->speed = 1;
 	te->clock_base = 1;			/* Save clock base */
 	memcpy(&te->tod_base, &tod_clock_base[1], 8);
-	store_tod_clock((__u64 *)&te->timestamp);
+	te->timestamp = get_tod_clock_fast();
 }
 
 /*