msm: mdss: Validate input in ioctl handler
msm: mdss: Validate input in ioctl handler

Inputs to the ioctl handler need to be validated and sanitized
to avoid null pointer dereferences

CRs-fixed: 482603
Change-Id: Id652da6ec943b660842141e66e228e14219a599d
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