brcmfmac: add device tree support for SDIO devices

brcmfmac devices can use an out-of-band interrupt on a GPIO line.
Currently this is specified using platform data. Add support for
specifying out-of-band interrupt via device tree.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
[arend@broadcom.com: conditionalize more of-code, use driver debug routines]
Signed-off-by: Arend van Spriel <arend@broadcom.com>
[hdegoede@redhat.com: drop clk / reg_on gpio handling, as there is no consensus
 on how to handle this yet]
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>