net: dsa: lan9303: Change lan9303_xxx_packet_processing() port param.

lan9303_enable_packet_processing, lan9303_disable_packet_processing()
Pass port number (0,1,2) as parameter instead of port offset.
Because other functions in the module pass port numbers.
And to enable simplifications in following patch.

Introduce lan9303_write_switch_port().

Signed-off-by: Egil Hjelmeland <privat@egil-hjelmeland.no>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>