As an operator I want to be able to specify additional kernel arguments
for nodes being inspected by ironic inspector so that I can pass
arguments to Ironic Python Agent (IPA).
A number of optional features in IPA are configured via kernel command
line arguments, e.g. ipa-collect-lldp.
This change allows additional kernel arguments to be provided for use
by the IPA ramdisk during inspection.
Change-Id: I547596a8108765383f291da690196f3222b59d79
Closes-Bug: #1685876