ARM: OMAP3: Add more GPIO mux options

This patch adds several new GPIO pins and updates
the pin naming comments.

The patch is based on earlier patches on linux-omap
list by Manikandan Pillai <mani.pillai@ti.com>,
Vaibhav Hiremath <hvaibhav@ti.com> and
David Brownell <dbrownell@users.sourceforge.net>.

Signed-off-by: Tony Lindgren <tony@atomide.com>