OMAP: DSS2: Add Color Phase Rotation support

Add Color Phase Rotation (CPR) support and sysfs files to enable CPR and
to set the CPR coefficient matrix.

CPR is enabled via manager?/cpr_enable file, and the coefficient matrix
is set via manager?/cpr_coef file. The values in cpr_coef are in the
following order:

RR RG RB GR GG GB BR BG BB

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>