net: introduce generic switch devices support

The goal of this is to provide a possibility to support various switch
chips. Drivers should implement relevant ndos to do so. Now there is
only one ndo defined:
- for getting physical switch id is in place.

Note that user can use random port netdevice to access the switch.

Signed-off-by: Jiri Pirko <jiri@resnulli.us>
Reviewed-by: Thomas Graf <tgraf@suug.ch>
Acked-by: Andy Gospodarek <gospo@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/MAINTAINERS b/MAINTAINERS
index 6b880de..3aba0ac 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -9059,6 +9059,13 @@
 F:	arch/*/kernel/pci-swiotlb.c
 F:	include/linux/swiotlb.h
 
+SWITCHDEV
+M:	Jiri Pirko <jiri@resnulli.us>
+L:	netdev@vger.kernel.org
+S:	Supported
+F:	net/switchdev/
+F:	include/net/switchdev.h
+
 SYNOPSYS ARC ARCHITECTURE
 M:	Vineet Gupta <vgupta@synopsys.com>
 S:	Supported