soc: st: set soc-level phy priority

Introducing MDIO and PHY support for stm32, phy driver gets
error (-116) if it tries to read phy chip id, since MDIO IP is
part of ETH IP, and eth hw module is still not initialized.

Forcing a priority that allows possibly connected PHY chip to be
detected properly at initial boot.

Signed-off-by: Angelo Dureghello <adureghello@baylibre.com>

Author: spectrum70

soc/st/stm32/Kconfig.defconfig

@@ -57,6 +57,10 @@ config CLOCK_CONTROL_INIT_PRIORITY
 	default 1
 	depends on CLOCK_CONTROL
 
+config PHY_INIT_PRIORITY
+	default 81
+	depends on NET_L2_ETHERNET && ETH_DRIVER
+
 config MEMC_STM32
 	default y
 	depends on MEMC