video: add amba-clcd prime-cell

This adds support for the CLCD logic cell. It accepts precompiled
register values for specific configuration through a board-supplied
data structure.  It is used by the Nomadik nhk8815, added by a later
patch in this series.

Signed-off-by: Alessandro Rubini <rubini@unipv.it>
Acked-by: Andrea Gallo <andrea.gallo@stericsson.com>