ethernet: stmmac: make DWMAC_STM32 depend on it's associated SoC

There's not much point, except compile test, enabling the stmmac
platform drivers unless the STM32 SoC is enabled. It's not
useful without it.
Signed-off-by: Peter Robinson <pbrobinson@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/stmicro/stmmac/Kconfig

@@ -107,7 +107,7 @@ config DWMAC_STI
 config DWMAC_STM32
 	tristate "STM32 DWMAC support"
 	default ARCH_STM32
-	depends on OF && HAS_IOMEM
+	depends on OF && HAS_IOMEM && (ARCH_STM32 || COMPILE_TEST)
 	select MFD_SYSCON
 	---help---
 	  Support for ethernet controller on STM32 SOCs.