msm: v4l2: remove dependency on MemoryHeapIon

MemoryHeapIon class was added in GB to replicate the
MemoryHeapPmem implementation. However, in ICS it is not
required since we use the new callback memory allocation
design.

Change-Id: I4cc93806a6ae3165b4354ea5ceefa70d5636f203

Conflicts:
	QCameraHWI.cpp
	QCameraHWI_Mem.cpp