smsc: Move the SMC (SMSC) drivers

Moves the SMC (SMSC) drivers into drivers/net/ethernet/smsc/ and the
necessary Kconfig and Makefile changes.  Also did some cleanup
of NET_VENDOR_SMC Kconfig tag for the 8390 based drivers.

CC: Nicolas Pitre <nico@fluxnic.net>
CC: Donald Becker <becker@scyld.com>
CC: Erik Stahlman <erik@vt.edu>
CC: Dustin McIntire <dustin@sensoria.com>
CC: Steve Glendinning <steve.glendinning@smsc.com>
CC: David Hinds <dahinds@users.sourceforge.net>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
diff --git a/drivers/net/ethernet/Kconfig b/drivers/net/ethernet/Kconfig
index ab591bb..ed5836c 100644
--- a/drivers/net/ethernet/Kconfig
+++ b/drivers/net/ethernet/Kconfig
@@ -18,5 +18,6 @@
 source "drivers/net/ethernet/chelsio/Kconfig"
 source "drivers/net/ethernet/intel/Kconfig"
 source "drivers/net/ethernet/qlogic/Kconfig"
+source "drivers/net/ethernet/smsc/Kconfig"
 
 endif # ETHERNET