mmc: atmel-mci: Add support for SDIO interrupts

Atmel-mci support for SDIO interrupts.  This adds the enable_sdio_irq()
function and the configuration of sdio irq mask per slot.  With this irq
mask information, we keep the idea of multiple slot per sd/mmc host (not
only A and B).  MMC_CAP_SDIO_IRQ is added according to slot configuration.

A new little function is added to run mmc_signal_sdio_irq() during
interrupt handling routine.

Signed-off-by: Anders Grahn <anders.grahn@hd-wireless.se>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Cc: Haavard Skinnemoen <hskinnemoen@atmel.com>
Cc: <linux-mmc@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>