OMAP: DSS2: DISPC: Prepare dispc_dump_regs() for shortening

Prepare dispc_dump_regs() to iterate over manager and overlay id's. Doing this
requires modifications of the macro "DUMPREG" which currently needs us to specify
the manager/overlay name to get the correct result. For example, in order to
print the register DISPC_TIMING_H(OMAP_DSS_CHANNEL_LCD), we can't iterate over
a varaible i and get the desired result through DUMPREG(DISPC_TIMING_H(i)).

Split the registers into 3 sections, the first with no arguments(common
registers), the second with one argument(manager/overlay id), and the third with
two arguments(overlay id and coefficient index), redefine DUMPREG macros for
each of these.
Signed-off-by: Archit Taneja <archit@ti.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>