net: fec: build fec.c and fec_ptp.c to one module

fec_ptp.ko can't run individually
rename fec.c to fec_main.c
Build fec.o and fec_ptp.o into one fec.ko
Remove unnessary EXPORT_SYMBOL in fec_ptp

Signed-off-by: Frank Li <Frank.Li@freescale.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/freescale/Makefile

@@ -2,7 +2,8 @@
 # Makefile for the Freescale network device drivers.
 #
 
-obj-$(CONFIG_FEC) += fec.o fec_ptp.o
+obj-$(CONFIG_FEC) += fec.o
+fec-objs :=fec_main.o fec_ptp.o
 obj-$(CONFIG_FEC_MPC52xx) += fec_mpc52xx.o
 ifeq ($(CONFIG_FEC_MPC52xx_MDIO),y)
 	obj-$(CONFIG_FEC_MPC52xx) += fec_mpc52xx_phy.o