romstage_handoff: add helper to determine resume status

Instead of having callers query the romstage handoff resume
status by inspecting the object themselves add
romstage_handoff_is_resume() so that the same information
can be queried easily.

Change-Id: I40f3769b7646bf296ee4bc323a9ab1d5e5691e21
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://review.coreboot.org/17647
Tested-by: build bot (Jenkins)
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-by: Furquan Shaikh <furquan@google.com>
6 files changed