net: fec_mxc: support i.MX8M with CLK_CCF

Add more clks for fec_mxc according to Linux Kernel 5.4.0-rc1
drivers/net/ethernet/freescale/fec_main.c.

Since i.MX8MQ not support CLK_CCF, so add a check to restrict
the code only effect when CONFIG_IMX8M and CONFIG_CLK_CCF both defined.

Reviewed-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Signed-off-by: Peng Fan <peng.fan@nxp.com>