sched/fair: Use mul_u32_u32()

While reading the code I encountered another site where we should be
using mul_u32_u32() because GCC just won't take a hint.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bsegall@google.com
Cc: dietmar.eggemann@arm.com
Cc: juri.lelli@redhat.com
Cc: ktkhai@virtuozzo.com
Cc: mgorman@suse.de
Cc: qais.yousef@arm.com
Cc: qperret@google.com
Cc: rostedt@goodmis.org
Cc: valentin.schneider@arm.com
Cc: vincent.guittot@linaro.org
Link: https://lkml.kernel.org/r/20191108131909.717931380@infradead.orgSigned-off-by: Ingo Molnar <mingo@kernel.org>

kernel/sched/fair.c

@@ -229,8 +229,7 @@ static u64 __calc_delta(u64 delta_exec, unsigned long weight, struct load_weight
 		}
 	}
 
-	/* hint to use a 32x32->64 mul */
-	fact = (u64)(u32)fact * lw->inv_weight;
+	fact = mul_u32_u32(fact, lw->inv_weight);
 
 	while (fact >> 32) {
 		fact >>= 1;