media: rkisp1: Simplify LSC x/y size and grad register macros

The LSC module x/y size and grad configuration is stored in a set of 4
indexed registers each. The rkisp1-regs.h header defines all those
registers, but only the first one in each set is used, with manual
calculation of addresses of subsequent registers. Simplifies this by
merging all 4 register macros into one that takes the index as a
parameter. No functional change intended.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Dafna Hirschfeld <dafna@fastmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>