net: dsa: lan9303: Documentation: Add missing word "Mbps"

Signed-off-by: NEgil Hjelmeland <privat@egil-hjelmeland.no>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Documentation/networking/dsa/lan9303.txt

 LAN9303 Ethernet switch driver
 ==============================
 
-The LAN9303 is a three port 10/100 ethernet switch with integrated phys for the
-two external ethernet ports. The third port is an RMII/MII interface to a host
-master network interface (e.g. fixed link).
+The LAN9303 is a three port 10/100 Mbps ethernet switch with integrated phys for
+the two external ethernet ports. The third port is an RMII/MII interface to a
+host master network interface (e.g. fixed link).
 
 
 Driver details