image-verify: Skip full verify for non-BMC images

The verifyFullImage() only supports verify BMC image, but does not apply
to other images like BIOS.

Skip doing verifyFullImage() for non-BMC images so that it is possible
to do BIOS code update when fieldMode is enabled.

Tested: Verify BIOS update is successful without verification error.
        Add related unit test case and verify it passes.

Signed-off-by: Lei YU <yulei.sh@bytedance.com>
Change-Id: Id9e72367bd2797f7a61c017b61fb81df1dd4d15c
3 files changed