ARM: dts: msm: align the splash memory size to 4MB

As splash memory is allocated from CMA heap, memory reservation
size is aligned to 4MB where as memblock_free is freeing only
requested size resulting in part of memory being always marked
as reserved. Fix this by requesting for size aligned to 4MB.

Change-Id: Ia2607201a0c6525f2487b85ce4d37d9644171efd
Signed-off-by: Shivaraj Shetty <shivaraj@codeaurora.org>
Signed-off-by: Gopal G Goberu <ggopal@qti.qualcomm.com>
Signed-off-by: Gopal G Goberu <ggober@codeaurora.org>