ARM: dts: msm: Specify WLED configuration for sdm855 CDP and MTP

Specify the required configuration for WLED device that is used
on sdm855 CDP and MTP platforms for backlight control.

Change-Id: I9d883c2105284133e99a9de0d436893e5beea929
Signed-off-by: Subbaraman Narayanamurthy <subbaram@codeaurora.org>