msm: mdss: Change ctl allocation
msm: mdss: Change ctl allocation

Need to assign ctl that is consistent with the type of mixer
allocated. Specifically for writeback mixers so that it can be
separated from interface ctls.

Change-Id: I7ae7316685286eab6202b91d8347bfd128b0a0b3
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