kernel: Make kmod-sfp depend on kmod-libphy

With kernel 5.4 kmod-sfp is depending on kmod-libphy, add this
missing dependency.

This also make phylink tristate so that kmod build work

Signed-off-by: Chen Minqiang <ptpt52@gmail.com>

package/kernel/linux/modules/netdevices.mk

@@ -111,6 +111,7 @@ $(eval $(call KernelPackage,libphy))
 define KernelPackage/phylink
   SUBMENU:=$(NETWORK_DEVICES_MENU)
   TITLE:=Model for MAC to optional PHY connection
+  DEPENDS:=+LINUX_5_4:kmod-libphy
   KCONFIG:=CONFIG_PHYLINK
   FILES:=$(LINUX_DIR)/drivers/net/phy/phylink.ko
   AUTOLOAD:=$(call AutoLoad,15,phylink,1)
@@ -1227,7 +1228,7 @@ $(eval $(call KernelPackage,sfc))
 define KernelPackage/sfp
   SUBMENU:=$(NETWORK_DEVICES_MENU)
   TITLE:=SFP cage support
-  DEPENDS:=+kmod-i2c-core +kmod-hwmon-core +kmod-phylink
+  DEPENDS:=+kmod-i2c-core +kmod-hwmon-core +kmod-phylink +LINUX_5_4:kmod-libphy
   KCONFIG:= \
 	CONFIG_SFP \
 	CONFIG_MDIO_I2C

target/linux/generic/hack-5.4/999-make-phylink-tristate.patch

@@ -0,0 +1,13 @@
+diff --git a/drivers/net/phy/Kconfig b/drivers/net/phy/Kconfig
+index e351d65533aa..ac3b50090502 100644
+--- a/drivers/net/phy/Kconfig
++++ b/drivers/net/phy/Kconfig
+@@ -239,7 +239,7 @@ endif
+ endif
+ 
+ config PHYLINK
+-	tristate
++	tristate "Phylink config support"
+ 	depends on NETDEVICES
+ 	select PHYLIB
+ 	select SWPHY