i40evf: return more useful error information

When verifying the API version (which is the first time the driver
communicates with the firmware and thus the PF driver), there are many
ways in which a failure can occur. There may be an error from the
firmware, there may be unresponsive firmware, there may be an error from
the PF driver, etc, etc.

Make this function return more useful information, instead of just -EIO.
Propagate FW errors back to the caller, and log a message if the PF
sends an invalid reply.

Change-ID: I3e9135a2b80f7acdb855f62f12b2b2668c9a8951
Signed-off-by: Mitch Williams <mitch.a.williams@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>