QcomModulePkg: Fix the OOB error when updating GPT partition

OOB maybe occur when updating GPT partition if the image size is
too small.

1. PrimaryGptHdr = (Gpt + BlkSz).
2. SecondaryGptHdr = Offset + BlkSz + PrimaryGptHdr.

Change-Id: Id1624ba23a5d5ea7159378760071579af645535a
1 file changed