msm: mdss: Remove background blending config for FB
msm: mdss: Remove background blending config for FB

Background blending for framebuffer isn't handled specially
in the driver. All blending assumes source over destination blending
from userspace.

CRs-fixed: 470535
Change-Id: Idbff01d9d976e57daaa2e5c128575a0dec07b38b
Signed-off-by: Sree Sesha Aravind Vadrevu <82b2d8b0bd3ba286d7f64b6c8e4070b752d7b65b@codeaurora.org>

TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas