Some type of BMCs don't support an IPMI option that disable the
behavior of boot device timeout, which makes them never get booted
from PXE.
This patch extends the fix [1] by adding a configuration option,
which provides the default ipmi behavior.
[1] https://review.openstack.org/#/c/616053
Additionally revising the variable/setting names based upon review
feedback and discussion that took place during the 20181210 weekly
ironic team meeting.
Change-Id: Ie049bbaf45aeab54c1272d1d561c5a6ca00dc34a
Story: 2002977
Task: 22985
The IPMI driver unconditionally instructed the BMC not automatically
clear boot flag valid bit if Chassis Control command not received within
60-second timeout (countdown restarts when a Chassis Control command is
received). Some BMCs do not support setting this. Sending the command
aborts the node boot.
A new driver option ``ipmi_disable_timeout`` is added to bypass
sending this command.
Change-Id: I1dda3cf3e4b7b888ed9d8931c8ede3a918dd01f4
Story: 2004266