msm: mdss: Sanitize panel resolutions properly

Currently there is no sanity checks present for panel
resolutions in wb driver. Add proper sanity checks
before configuring with new set of panel resolutions.

Change-Id: Ibdada9e1711f59785d11cc4821105e2e1849b0f3
Signed-off-by: Jayant Shekhar <jshekhar@codeaurora.org>