[rhel6-branch] Fix generation of ppc64 images

[David Shea]

The size check for ppc64.img was happening before the file was generated. This
fixes that, hopefully.

The first patch is a big gnarly whitespace change, because it's hard enough to
figure out what's going on in this script when the if blocks line up right.
Replaced all the tabs with spaces since that was probably half the problem
anyway.