linux-wandboard

ENGR00161207 - FEC: Add IEEE 1588 driver for imx6

- Support time stamp sync with networking master timer.
- Support ipg 40MHz clock, and precision is about 20ns.
- Don't support ipg 66MHz clock.
- Test flow:
	1. Enable CONFIG_FEC_1588 in imx6_defconfig file.
	2. Select pll3 for ipg clk 40M in uboot plugin code.
		I. set reg 0x20c8028 value to 0x10000;
		II.set reg 0x20c8024 value to 0x3040;
		III. set reg 0x20c4014[25] to 0x1
		IV. set reg 0x20c4014[12:10] to 0x5
	3. Rebuid uboot and setup the ethernet environment.
	4. Run the 1588 stack ptp_main in master and slave.

Signed-off-by: Fugang Duan  <B38611@freescale.com>