This implements a state machine intended to support the userland tool for
updating the device eeprom. The state machine implements one-shot reads,
writes, multi-step write sessions, and checksum requests. If we're in the middle
of a multi-step write session, no one should fire off other writes, however, one
shot reads are valid. The userland tool is expected to keep track of its session
status, arrange the placement and ordering of the writes, and deal with the
checksum requirement.

This patch also adds nvmupdate support to ethtool callbacks.
The get_eeprom() and set_eeprom() services in ethtool are used here to
facilitate the userland NVMUpdate tool.  The 'magic' value in the get and
set commands is used to pass additional control information for managing
the read and write steps.

The read operation works both as normally expected in the standard ethtool
method, as well as with the extra NVM controls.  The write operation
works only for the expanded NVM functions - the normal ethtool method is
not allowed because of the NVM semaphore management needed for multipart
writes, as well as the checksum requirement.

Change-ID: I1d84a170153a9f437906744e2e350fd68fe7563d
Signed-off-by: Shannon Nelson <shannon.nelson@intel.com>
Tested-by: Jim Young <jamesx.m.young@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>