The support for DSA Ethernet switch chips depends on TCP/IP networking,
thus explicit that HAVE_NET_DSA depends on INET.

DSA uses SWITCHDEV, thus select it instead of depending on it.
Signed-off-by: NVivien Didelot <vivien.didelot@savoirfairelinux.com>
Reviewed-by: NAndrew Lunn <andrew@lunn.ch>
Reviewed-by: NFlorian Fainelli <f.fainelli@gmail.com>
Tested-by: NRandy Dunlap <rdunlap@infradead.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>