ARM: dts: imx25-pinfunc: Add several pinfunctions

This patch adds some not yet defined pinfunctions. It also adds two
comments about mistakes in the i.MX25 reference manual so it is easier
to spot the difference between reference manual and pinfunction
definitions.

Signed-off-by: Markus Pargmann <mpa@pengutronix.de>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>