ARM: mmp: remove device definitions

Since all board support is now gone, a lot of code in the
platform is no longer called and can be removed as well.
The remaining parts are:

 * The interrupt numbers for pxa910 are still needed for the
   power management support.

 * The 'mfp' device is still statically initialized from
   platform code, though this could be moved into the
   pinctrl code

 * The CPU identification code is used for the cpu_is_mmp*()
   macros.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>