mmc: simplify mmc_cd_gpio_request() by removing two parameters

Calculate the IRQ number, using gpio_to_irq() and use fixed flags: trigger
on both edges. This makes two out of four arguments of the
mmc_cd_gpio_request() function redundant.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Chris Ball <cjb@laptop.org>