net: sfp: move sfp sub-state machines into separate functions

Move the SFP sub-state machines out of the main state machine function,
in preparation for it doing a bit more with the device state.  By doing
so, we ensure that our debug after the main state machine is always
printed.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>