ARM: dts: imx25-pinfunc: more defines

Add some defines currently missing, fix ordering to make the list
sorted by (mux_reg, mux_val), make sure pins are grouped by mux_reg.

The same definitions are missing from the old pinmux header
(arch/arm/mach-imx/iomux-mx25.h) but as only legacy machine support uses
that and therefor the existing list is obviously good enough I didn't
spend the effort to add the corresponding definitions there, too.

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