Camera: Preview buffer length correction in PCB

Gralloc is creating the buffers in an aligned fashion because of which buffer size created for
each preview frame is little more than the required (width*height*1.5).
This fix corrects the memory back to original ((width*height*1.5)) by removing the extra space created while doing PCB.

This is port of:
https://www.codeaurora.org/cgit/quic/la/platform/hardware/qcom/camera/commit?id=16f3d71795422810d16ca68195dc7cf69cf19c6a
Coding style unification and further code cleanup

Unified coding style,
Remove unused DispMemPool definition and mPreviewHeap,
Reduced number of printed logs during normal operation,
Other code cleanups