For FT8006S HLT LCD because the FT8006S IC spec backlight register, we add the mipi_dsi_dcs_set_display_brightness_2bytes_2th_low4bit the function. Change-Id: Ib77bf0981ace8c4f9cf77c69a70696ec2075fcae Reviewed-on: https://gerrit.mot.com/2061265 SME-Granted: SME Approvals Granted SLTApproved: Slta Waiver Tested-by: Jira Key Reviewed-by: Suting Xie <xiest1@motorola.com> Submit-Approved: Suting Xie <xiest1@motorola.com>