Revert "bcm2708: fix gpio_to_irq() name clash"

This reverts commit f04ff75d39215e8b0ecd20c027abda45bf741213.

Conflicts:
	arch/arm/mach-bcm2708/bcm2708_gpio.c
Merge pull request #507 from jfasch/rpi-3.12.y-fix-gpio_to_irq

Please pull: NEED_MACH_GPIO_H vs. gpio_to_irq() woes