Move several macros and structures from the Freescale DIU driver's header
file into the source file, because they're only used by that file.  Also
delete a few unused macros.

The diu and diu_ad structures cannot be moved because they're being used
by the MPC5121 platform file.  A future patch eliminate the need for
the platform file to access these structs, so they'll be moved also.
Signed-off-by: NTimur Tabi <timur@freescale.com>
Signed-off-by: NFlorian Tobias Schandinat <FlorianSchandinat@gmx.de>