GMAC: modify CRU config for Rockchip RK3288 SoCs integrated GMAC

modify CRU config for GMAC driver

changes since v2:
1. remove SCLK_MAC_PLL

Signed-off-by: Roger Chen <roger.chen@rock-chips.com>
Signed-off-by: David S. Miller <davem@davemloft.net>