Convert CONFIG_FSL_MEMAC et al to Kconfig

This converts the following to Kconfig:
   CONFIG_FSL_MEMAC
   CONFIG_SYS_MEMAC_LITTLE_ENDIAN

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig
index 21d6481..93e7dbe 100644
--- a/drivers/net/Kconfig
+++ b/drivers/net/Kconfig
@@ -375,6 +375,7 @@
 
 config SYS_FMAN_V3
 	bool
+	select FSL_MEMAC
 	help
 	  SoC has FMan v3 with mEMAC