mmc: mtk-sd: Re-store SDIO IRQs mask at system resume

In cases when SDIO IRQs have been enabled, runtime suspend is prevented by
the driver. However, this still means msdc_runtime_suspend|resume() gets
called during system suspend/resume, via pm_runtime_force_suspend|resume().

This means during system suspend/resume, the register context of the mtk-sd
device most likely loses its register context, even in cases when SDIO IRQs
have been enabled.

To re-enable the SDIO IRQs during system resume, the mtk-sd driver
currently relies on the mmc core to re-enable the SDIO IRQs when it resumes
the SDIO card, but this isn't the recommended solution. Instead, it's
better to deal with this locally in the mtk-sd driver, so let's do that.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
diff --git a/drivers/mmc/host/mtk-sd.c b/drivers/mmc/host/mtk-sd.c
index 6946bb0..189e426 100644
--- a/drivers/mmc/host/mtk-sd.c
+++ b/drivers/mmc/host/mtk-sd.c
@@ -2435,6 +2435,9 @@ static void msdc_restore_reg(struct msdc_host *host)
 	} else {
 		writel(host->save_para.pad_tune, host->base + tune_reg);
 	}
+
+	if (sdio_irq_claimed(host->mmc))
+		__msdc_enable_sdio_irq(host, 1);
 }
 
 static int msdc_runtime_suspend(struct device *dev)