net: dsa: tag_lan9303: Fix __be16 warnings

net/dsa/tag_lan9303.c:76:24: warning: incorrect type in assignment (different base types)
net/dsa/tag_lan9303.c:76:24:    expected unsigned short [usertype]
net/dsa/tag_lan9303.c:76:24:    got restricted __be16 [usertype]
net/dsa/tag_lan9303.c:80:24: warning: incorrect type in assignment (different base types)
net/dsa/tag_lan9303.c:80:24:    expected unsigned short [usertype]
net/dsa/tag_lan9303.c:80:24:    got restricted __be16 [usertype]
net/dsa/tag_lan9303.c:106:31: warning: restricted __be16 degrades to integer
net/dsa/tag_lan9303.c:111:24: warning: cast to restricted __be16
net/dsa/tag_lan9303.c:111:24: warning: cast to restricted __be16
net/dsa/tag_lan9303.c:111:24: warning: cast to restricted __be16
net/dsa/tag_lan9303.c:111:24: warning: cast to restricted __be16

Make use of __be16 where appropriate to fix these warnings.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>