clk: rockchip: rename rv1108 macphy clock to mac

This MAC has no internal phy for rv1108 and the whole clock
infrastructure hasn't been used yet, so is safe to fix.

Signed-off-by: Elaine Zhang <zhangqing@rock-chips.com>
Reviewed-by: David Wu <david.wu@rock-chips.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>