[ARM] 4634/1: DaVinci GPIO header build fix

This fixes a build problem with GPIOs on DaVinci.  Since it inlines
operations for on-chip GPIOs, it needs some headers to support those
direct register accesses.  Those headers won't be included on other
platforms, since they don't have that optimization.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Acked-by: Kevin Hilman <khilman@mvista.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>