msm: mdss:Add splash logo configuration entry in fb

Framebuffer driver displays penguin logo image
for all targets. Bootloader also displays the
same image. However, customer has to change this
boot image at two places if they want to display
different image than penguin logo. This change allows
customer to disable/enable the splash image from
framebuffer driver.

Change-Id: I56e78ce93aa8c218adffef03bfebd462d6bda254
Signed-off-by: Dhaval Patel <pdhaval@codeaurora.org>