ARM: dts: nokia n900: update dts with camera support

Add camera support to N900 dts. Also add a note about MMC & debugging.

Signed-off-by: Pavel Machek <pavel@ucw.cz>
Acked-by: Pali Rohár <pali.rohar@gmail.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>