Replace "select NET_SWITCHDEV" vs "depends on NET_SWITCHDEV" to fix Kconfig
warning with CONFIG_COMPILE_TEST=y

WARNING: unmet direct dependencies detected for NET_SWITCHDEV
  Depends on [n]: NET [=y] && INET [=n]
  Selected by [y]:
  - TI_CPSW_SWITCHDEV [=y] && NETDEVICES [=y] && ETHERNET [=y] && NET_VENDOR_TI [=y] && (ARCH_DAVINCI || ARCH_OMAP2PLUS || COMPILE_TEST [=y])

because TI_CPSW_SWITCHDEV blindly selects NET_SWITCHDEV even though
INET is not set/enabled, while NET_SWITCHDEV depends on INET.
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Fixes: ed3525ed ("net: ethernet: ti: introduce cpsw switchdev based driver part 1 - dual-emac")
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org> # build-tested
Signed-off-by: David S. Miller <davem@davemloft.net>