ethtool: cmis_fw_update: add a layer for supporting firmware update using CDB

According to the CMIS standard, the firmware update process is done using
a CDB commands sequence.

Implement a work that will be triggered from the module layer in the
next patch the will initiate and execute all the CDB commands in order, to
eventually complete the firmware update process.

This flashing process includes, writing the firmware image, running the new
firmware image and committing it after testing, so that it will run upon
reset.

This work will also notify user space about the progress of the firmware
update process.

Signed-off-by: Danielle Ratson <danieller@nvidia.com>
Reviewed-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>