net: mscc: Move mac_table_add function into different file.

Move the function mac_table_add into a different file,
so it can be reused.

Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>
diff --git a/drivers/net/mscc_eswitch/Makefile b/drivers/net/mscc_eswitch/Makefile
index 20e8e4c..704f854 100644
--- a/drivers/net/mscc_eswitch/Makefile
+++ b/drivers/net/mscc_eswitch/Makefile
@@ -1,2 +1,2 @@
 
-obj-$(CONFIG_MSCC_OCELOT_SWITCH) += ocelot_switch.o mscc_miim.o mscc_xfer.o
+obj-$(CONFIG_MSCC_OCELOT_SWITCH) += ocelot_switch.o mscc_miim.o mscc_xfer.o mscc_mac_table.o