mmc: meson-gx: fix SDIO mode if cap_sdio_irq isn't set

mmc: meson-gx: fix SDIO mode if cap_sdio_irq isn't set

Some SDIO WiFi modules stopped working after SDIO interrupt mode
was added if cap_sdio_irq isn't set in device tree. This patch was
confirmed to fix the issue.

Fixes: 066ecde6d826 ("mmc: meson-gx: add SDIO interrupt support")
Reported-by: Geraldo Nascimento <geraldogabriel@gmail.com>
Tested-by: Geraldo Nascimento <geraldogabriel@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Link: https://lore.kernel.org/r/816cba9f-ff92-31a2-60f0-aca542d1d13e@gmail.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>