mmc: sunxi: add MMC_CAP_SDIO_IRQ capability

When the sunxi mmc-controller code was initially merged MMC_CAP_SDIO_IRQ was
not added to the host caps because of issues with some sdio wifi modules.

It turns out that these issues have nothing to do with using sdio-irq support,
they also happen with oob interrupts. Since the hardware supports sdio-irq
everywhere, and since the one reason to not claim the capability is gone,
add MMC_CAP_SDIO_IRQ to the default host caps.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>