mmc: omap_hsmmc: Enable SDIO interrupt

mmc: omap_hsmmc: Enable SDIO interrupt

There have been various patches floating around for enabling
the SDIO IRQ for hsmmc, but none of them ever got merged.

Probably the reason for not merging the SDIO interrupt patches
has been the lack of wake-up path for SDIO on some omaps that
has also needed remuxing the SDIO DAT1 line to a GPIO making
the patches complex.

This patch adds the minimal SDIO IRQ support to hsmmc for
omaps that do have the wake-up path. For those omaps, the
DAT1 line need to have the wake-up enable bit set, and the
wake-up interrupt is the same as for the MMC controller.

This patch has been tested on am3730 es1.2 with mwifiex
connected to MMC3 with mwifiex waking to Ethernet traffic
from off-idle mode. Note that for omaps that do not have
the SDIO wake-up path, this patch will not work for idle
modes and further patches for remuxing DAT1 to GPIO are
needed.

Based on earlier patches [1][2] by David Vrabel
<david.vrabel@csr.com>, Steve Sakoman <steve@sakoman.com>

For now, only support SDIO interrupt if we are booted with
a separate wake-irq configued via device tree. This is
because omaps need the wake-irq for idle states, and some
omaps need special quirks. And we don't want to add new
legacy mux platform init code callbacks any longer as we
are moving to DT based booting anyways.

To use it, you need to specify the wake-irq using the
interrupts-extended property.

[1] http://www.sakoman.com/cgi-bin/gitweb.cgi?p=linux.git;a=commitdiff_plain;h=010810d22f6f49ac03da4ba384969432e0320453
[2] http://comments.gmane.org/gmane.linux.kernel.mmc/20446

Acked-by: Balaji T K <balajitk@ti.com>
Signed-off-by: Andreas Fenkart <afenkart@gmail.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>