Implement Network Settings Override

We want to implement the network settings override functionality.
This is an OEM boot parameter selector, using parameter ID 0x61.

The first byte of the parameter data is the same as parameter ID 5 (ie,
the valid flag in the top bit). Persistency doesn't matter here, as
petitboot will not clear out this setting.

The rest of the parameter data is a host network settings description.
For other BMC firmware, the BMC just treats this as opaque (the BMC will
just return the same data (including that data1 byte), in response to a
Get System Boot Option). For OpenBMC, we may want the BMC to know how to
construct that data; the spec for that is at:

http://ozlabs.org/~sam/ipmi-network-format

Closes openbmc/openbmc#267

Change-Id: I2af8776718deda97acf90d10504783085ccf7323
Signed-off-by: Ratan Gupta <ratagupt@in.ibm.com>
3 files changed