ARM: dts: Fix gpio interrupts for dm816x

Commit 7800064b ("ARM: dts: Add basic dm816x device tree
configuration") added basic devices for dm816x, but I was not able
to test the GPIO interrupts earlier until I found some suitable pins
to test with. We can mux the MMC card detect and write protect pins
from SD_SDCD and SD_SDWP mode to use a normal GPIO interrupts that
are also suitable for the MMC subsystem.

This turned out several issues that need to be fixed:

- I set the GPIO type wrong to be compatible with omap3 instead
  of omap4. The GPIO controller on dm816x has EOI interrupt
  register like omap4 and am335x.

- I got the GPIO interrupt numbers wrong as each bank has two
  and we only use one. They need to be set up the same way as
  on am335x.

- The gpio banks are missing interrupt controller related
  properties.

With these changes the GPIO interrupts can be used with the
MMC card detect pin, so let's wire that up. Let's also mux all
the MMC lines for completeness while at it.

For the first GPIO bank I tested using GPMC lines temporarily
muxed to GPIOs on the dip switch 10.

Cc: Brian Hutchinson <b.hutchman@gmail.com>
Cc: Matthijs van Duin <matthijsvanduin@gmail.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>