QcomModulePkg: Update image size check for BootLinux

1. ImageBuffer is allocated and has rounded to page. no need to check
the 64bit integer overflow, just need to add the range check to make
sure the image offset doesn't go beyond the kernal size

2. Add integer overflow check

Change-Id: I297a90f3da121ed6debf5102833a33ef5f769f8f
1 file changed