msm_fb: Copy splash image to kernel memory

The bootloader memory from which the splashscreen is shown
gets reclaimed before frame update happens from framework.
Hence, copy the splash image to a local buffer as soon as
display is initialized. This will ensure proper continuous
splashscreen functionality.

Change-Id: I9e9b45b001ab390959bde5039ed8b859361ec888
Signed-off-by: Shivaraj Shetty <shivaraj@codeaurora.org>