net: Revert ARCNET and PHYLIB to tristate options

commit 88491d8103498a6166f70d5999902fec70924314 ("drivers/net: Kconfig
& Makefile cleanup") changed the type of these options to bool, but
they select code that could (and still can) be built as modules.

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/phy/Kconfig b/drivers/net/phy/Kconfig
index bb88e12..a702443 100644
--- a/drivers/net/phy/Kconfig
+++ b/drivers/net/phy/Kconfig
@@ -3,7 +3,7 @@
 #
 
 menuconfig PHYLIB
-	bool "PHY Device support and infrastructure"
+	tristate "PHY Device support and infrastructure"
 	depends on !S390
 	depends on NETDEVICES
 	help