mmc: mmci: Break IRQ status loop when all zero

We iterate an extra time through the IRQ status handling
loop despite nothing had fired. Enabling the debug prints:

mmci-pl18x 80005000.mmc: op 01 arg 00000000 flags 000000e1
mmci-pl18x 80005000.mmc: irq0 (data+cmd) 00000001
mmci-pl18x 80005000.mmc: irq0 (data+cmd) 00000000
mmci-pl18x 80005000.mmc: op 01 arg 40ff8080 flags 000000e1
mmci-pl18x 80005000.mmc: irq0 (data+cmd) 00000001
mmci-pl18x 80005000.mmc: irq0 (data+cmd) 00000000

It is pointless to loop through the function when status
is zero. Just break the loop if the status is zero.
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20220416224549.627623-1-linus.walleij@linaro.orgSigned-off-by: NUlf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/mmci.c

@@ -1619,6 +1619,8 @@ static irqreturn_t mmci_irq(int irq, void *dev_id)
 
 	do {
 		status = readl(host->base + MMCISTATUS);
+		if (!status)
+			break;
 
 		if (host->singleirq) {
 			if (status & host->mask1_reg)