ethtool: Add flashing transceiver modules' firmware notifications ability

Add progress notifications ability to user space while flashing modules'
firmware by implementing the interface between the user space and the
kernel.

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