NET: FEC: dynamtic check DMA desc buff type

MX6 and mx28 support enhanced DMA descriptor buff to support 1588
ptp. But MX25, MX3x, MX5x can't support enhanced DMA descriptor buff.
Check fec type and choose correct DMA descriptor buff type.

Remove static config CONFIG_FEC_PTP.
ptp function will be auto detected.

Signed-off-by: Frank Li <Frank.Li@freescale.com>
Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/freescale/Makefile b/drivers/net/ethernet/freescale/Makefile
index d4d19b3..b7d58fe 100644
--- a/drivers/net/ethernet/freescale/Makefile
+++ b/drivers/net/ethernet/freescale/Makefile
@@ -2,8 +2,7 @@
 # Makefile for the Freescale network device drivers.
 #
 
-obj-$(CONFIG_FEC) += fec.o
-obj-$(CONFIG_FEC_PTP) += fec_ptp.o
+obj-$(CONFIG_FEC) += fec.o fec_ptp.o
 obj-$(CONFIG_FEC_MPC52xx) += fec_mpc52xx.o
 ifeq ($(CONFIG_FEC_MPC52xx_MDIO),y)
 	obj-$(CONFIG_FEC_MPC52xx) += fec_mpc52xx_phy.o