MII: fix Kconfig dependencies for MII

MII Kconfig option is apart of the core networking drivers and
by default NET_CORE is enabled so drivers selecting MII will
have MII enabled as well.  It was found using the randconfig
option during testing, MII would be selected but NET_CORE
could be disabled.  This caused a dependency error.

Resolved the dependency by selecting NET_CORE when MII is
selected.

Reported-by: Emil Tantilov <emil.s.tantilov@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/micrel/Kconfig b/drivers/net/ethernet/micrel/Kconfig
index bd090db..d10c2e1 100644
--- a/drivers/net/ethernet/micrel/Kconfig
+++ b/drivers/net/ethernet/micrel/Kconfig
@@ -22,6 +22,7 @@
 config ARM_KS8695_ETHER
 	tristate "KS8695 Ethernet support"
 	depends on ARM && ARCH_KS8695
+	select NET_CORE
 	select MII
 	---help---
 	  If you wish to compile a kernel for the KS8695 and want to
@@ -38,6 +39,7 @@
 config KS8851
 	tristate "Micrel KS8851 SPI"
 	depends on SPI
+	select NET_CORE
 	select MII
 	select CRC32
 	---help---
@@ -46,6 +48,7 @@
 config KS8851_MLL
 	tristate "Micrel KS8851 MLL"
 	depends on HAS_IOMEM
+	select NET_CORE
 	select MII
 	---help---
 	  This platform driver is for Micrel KS8851 Address/data bus
@@ -54,6 +57,7 @@
 config KSZ884X_PCI
 	tristate "Micrel KSZ8841/2 PCI"
 	depends on PCI
+	select NET_CORE
 	select MII
 	select CRC32
 	---help---