msm: mdss: Check ctl in mdss_mdp_mixer_get before using
msm: mdss: Check ctl in mdss_mdp_mixer_get before using

Put NULL check for ctl before using in mdss_mdp_mixer_get.

Change-Id: Ia1bc035df46c9e237c244623e61a6802cf0d9110
Signed-off-by: Pawan Kumar <80497aab8b412ead203a66b497b6d50dbfda12d8@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