msm_fb: display: add config of wb_mux_sel during update
msm_fb: display: add config of wb_mux_sel during update

To make sure for each writeback play the reg is configured and avoid
mdp hang.

Change-Id: I29bdc31f27accca84e7add126c1c1e3c8a78fa15
Signed-off-by: Huaibin Yang <5ee695045ff23377b540344f819c3ec194b2e2c6@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