Fix hyper-v vhd real size bigger than flavor issue

In hyper-v, after deploy the image, real vhd file size will be
extended from flavor size plus vhd metadata size, this patch
fix this issue by check the vhd type and minus the vhd metadata
size according to the specific vhd type.

Fixes bug #1177927

Change-Id: I51223f4f778f33e73dce1e0f53e23e8d7ac77904
Merge "Fix hyper-v vhd real size bigger than flavor issue"