Define and use OMAP4 GPIO macros rather than magic constants.
Add and use meaningful macro names for OMAP4 GPIO addresses, and add a
comment to explain the 0x100 offset for OMAP4.
Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>