OMAP2420: hwmod data: Add GPIO

Add GPIO hwmod data for OMAP2420 and add the required
GPIO device attributes in the gpio header file

Also remove "omap24xx.h" header file as it is not required
anymore.

Signed-off-by: Charulatha V <charu@ti.com>
Acked-by: Benoit Cousson <b-cousson@ti.com>
Acked-by: Kevin Hilman <khilman@deeprootsystems.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>