sched,mmc: Convert to sched_set_fifo*()

Because SCHED_FIFO is a broken scheduler model (see previous patches)
take away the priority field, the kernel can't possibly make an
informed decision.

In this case, use fifo_low, because it only cares about being above
SCHED_NORMAL. Effectively no change in behaviour.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/core/sdio_irq.c

@@ -139,11 +139,10 @@ EXPORT_SYMBOL_GPL(sdio_signal_irq);
 static int sdio_irq_thread(void *_host)
 {
 	struct mmc_host *host = _host;
-	struct sched_param param = { .sched_priority = 1 };
 	unsigned long period, idle_period;
 	int ret;
 
-	sched_setscheduler(current, SCHED_FIFO, &param);
+	sched_set_fifo_low(current);
 
 	/*
 	 * We want to allow for SDIO cards to work even on non SDIO