media: rkisp1: Use correct macro for gradient registers
The rkisp1_lsc_config() function incorrectly uses the
RKISP1_CIF_ISP_LSC_SECT_SIZE() macro for the gradient registers. Replace
it with the correct macro, and rename it from
RKISP1_CIF_ISP_LSC_GRAD_SIZE() to RKISP1_CIF_ISP_LSC_SECT_GRAD() as the
corresponding registers store the gradients for each sector, not a size.
This doesn't cause any functional change as the two macros are defined
identically (the size and gradient registers store fields in the same
number of bits at the same positions).