msm: mdss: continuous splash screen support on 8x10

This adds the continuous splash screen support on
8x10.  At the kernel bootup time, display driver
will copy the splash image from the LK to its own
allocated memory, and keep the display on with the
splash image until the first UI update.

Change-Id: I13b2c7fa92d1bbd03fa7bf641d9c54b9ac0a8223
Signed-off-by: Terence Hampson <thampson@codeaurora.org>
Signed-off-by: Xiaoming Zhou <zhoux@codeaurora.org>