Don't rely on dimensions given in desc.txt

It is possible for a boot animation to have images that are not
the same dimensions as those given in the desc.txt.  For this
reason we should not rely on those dimensions when allocating
bitmaps.

Change-Id: Ic4996c419d542bdcfbec5ebf6df3c9d6364e5af6
Merge "Don't rely on dimensions given in desc.txt" into cm-11.0