flashupdate: Add libhoth dependency use libhoth talking to hoth to support bios key rotation Tested: Refer to bug comment Fusion-Link: http://fusion2/N/A Google-Bug-Id: 425993058 Change-Id: I3d2c282442fd07eff0071a627d36c6b4043ae630 Signed-off-by: Dan Zhang <zhdaniel@google.com>