ARM: OMAP: use gpio_to_irq

Have most uses of OMAP_GPIO_IRQ() use gpio_to_irq() instead.
Calls used for table initialization are left alone, at least
this time around.

(This patch is for code in both the OMAP tree and mainline.)

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Tony Lindgren <tony@atomide.com>