msm: mdss: dsi: fix NULL pointer access while changing resolution

During "adb shell stop/start", CTL structure gets destroyed.
Add check for CTL pointer before trying to change resolution. Remove
additional frame rate and clock rate parsing since it already done
while parsing the timing settings. Initialize timing structure
entries to zero before updating the structure.

CRs-fixed: 873962
Change-Id: Iebb2168eef0e002b98afa46b510b028f8ea183b1
Signed-off-by: Chandan Uddaraju <chandanu@codeaurora.org>