net: microchip: sparx5: fix kconfig warning

PHY_SPARX5_SERDES depends on OF so SPARX5_SWITCH should also depend
on OF since 'select' does not follow any dependencies.

WARNING: unmet direct dependencies detected for PHY_SPARX5_SERDES
  Depends on [n]: (ARCH_SPARX5 || COMPILE_TEST [=n]) && OF [=n] && HAS_IOMEM [=y]
  Selected by [y]:
  - SPARX5_SWITCH [=y] && NETDEVICES [=y] && ETHERNET [=y] && NET_VENDOR_MICROCHIP [=y] && NET_SWITCHDEV [=y] && HAS_IOMEM [=y]

Fixes: 3cfa11b ("net: sparx5: add the basic sparx5 driver")
Signed-off-by: Randy Dunlap <[email protected]>
Cc: Lars Povlsen <[email protected]>
Cc: Steen Hegelund <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: "David S. Miller" <[email protected]>
Cc: Jakub Kicinski <[email protected]>
Cc: [email protected]
Signed-off-by: David S. Miller <[email protected]>

Author: rddunlap

drivers/net/ethernet/microchip/sparx5/Kconfig

@@ -2,6 +2,7 @@ config SPARX5_SWITCH
 	tristate "Sparx5 switch driver"
 	depends on NET_SWITCHDEV
 	depends on HAS_IOMEM
+	depends on OF
 	select PHYLINK
 	select PHY_SPARX5_SERDES
 	select RESET_CONTROLLER