mdss: mdp: Free splash memory properly

We were calling free_bootmem_late, which is a __init function,
from a none __init context. We are moving to free_reserved_page.

Change-Id: I53b3b781201d46a6894f8d9fdfab1c3c5f3802b8
Signed-off-by: Terence Hampson <thampson@codeaurora.org>