target: msm8974: edp back light through lpg channel 8
target: msm8974: edp back light through lpg channel 8

Currently edp back light is controlled by pulling high at
pm-gpio-36 directly. This cause back light inverted at
Android kernel. Fixed back light inverted problem by
control back light through lpg channel #8.

CRs-Fixed: 538278
Change-Id: Ia63bdc1e94ac4600252f215b039cf2227c9c08f9

mozilla-b2g/fairphone2_kernel_lk,mozilla-b2g/fairphone2_kernel_lk,t2m-foxfone/android_kernel_lk,t2m-foxfone/kernel_lk,idor/dk50-bootable_bootloader_lk,idor/dk50-bootable_bootloader_lk,t2m-foxfone/android_kernel_lk,t2m-foxfone/android_kernel_lk,lg-devs/g2-bootloader,mozilla-b2g/kernel_lk,lg-devs/g2-bootloader,mozilla-b2g/kernel_lk,t2m-foxfone/kernel_lk,t2m-foxfone/kernel_lk,lg-devs/g2-bootloader,Redmi-dev/android_bootable_lk,Redmi-dev/android_bootable_lk,mozilla-b2g/kernel_lk,mozilla-b2g/fairphone2_kernel_lk,Redmi-dev/android_bootable_lk,t2m-foxfone/android_kernel_lk,idor/dk50-bootable_bootloader_lk,idor/dk50-bootable_bootloader_lk,mozilla-b2g/kernel_lk,lg-devs/g2-bootloader,t2m-foxfone/kernel_lk,Redmi-dev/android_bootable_lk,mozilla-b2g/fairphone2_kernel_lk,mozilla-b2g/fairphone2_kernel_lk,Redmi-dev/android_bootable_lk,idor/dk50-bootable_bootloader_lk,lg-devs/g2-bootloader,mozilla-b2g/kernel_lk,t2m-foxfone/android_kernel_lk,t2m-foxfone/kernel_lk