msm: mdss: fix the panel color distortion issue for RGB565 format

For the color format RGB565, the pack pattern was set to BGR instead
of RGB, causing the red and blue color swapping on the panel.

Change-Id: Ib9233a93676e7d5d40f134f9a1657781c631ebdd
Signed-off-by: Xiaoming Zhou <zhoux@codeaurora.org>