leds: flash: leds-qcom-flash: Add a separate register map for PMI8998

The 3-channel flash module in PMI8998 has several registers different
than the others, such as: torch_clamp. Add different register fields
for it.

Signed-off-by: Fenglin Wu <fenglin.wu@oss.qualcomm.com>
Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Link: https://lore.kernel.org/r/20250729-fix-torch-clamp-issue-v2-2-9b83816437a3@oss.qualcomm.com


Signed-off-by: Lee Jones <lee@kernel.org>