net/fec: add imx6q enet support

The imx6q enet is a derivative of imx28 enet controller.  It fixed
the frame endian issue found on imx28, and added 1 Gbps support.

It also fixes a typo on vendor name in Kconfig.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>