ARM: OMAP: gpio init section cleanups

Minor GPIO cleanups:  remove needless #include, and omap_gpio_init()
should be __init, as well as all the board init code calling it.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>