msm: mdss: Avoid memcopy in dsi driver

Update dsi panel code to use controller variable directly to
avoid memcopy in dsi driver. This simplifies the code and
avoids usage of multiple structures for same configurations.

Change-Id: I1625190213c8844ce99a9812892531ac5b7a64fb
Signed-off-by: Dhaval Patel <pdhaval@codeaurora.org>