drivers/video: fsl-diu-fb: merge diu_pool into fsl_diu_data

The diu_pool structure contains diu_addr objects for various objects
allocated in DMA space that are used by the DIU, but the only instance
of this structure is a global variable, 'pool'.  Eliminate 'pool' by
merging its fields into the fsl_diu_data structure, which is instantiated
on the heap for each DIU controller found.

Signed-off-by: Timur Tabi <timur@freescale.com>
Signed-off-by: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>