msm: Increase memory to Ion EBI1 heap

Instead of calling allocate contiguous memory directly,
video clients now call ion_alloc. Take 6MB from the block
for allocate_contiguous_memory and give it to ion instead.

Change-Id: I071edbe4d581c574eeb7e19b720df08b916611e1
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>