mmc: sdhci: Drop redundant check in sdhci_ack_sdio_irq()

The sdhci_ack_sdio_irq() is called only when SDIO IRQs are enabled.
Therefore, let's drop the redundant check of the internal
SDHCI_SDIO_IRQ_ENABLED flag and just re-enable the IRQs immediately.

Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>