rockchip: clk: rk3288: Drop use of SCLK_MAC_PLL

rockchip: clk: rk3288: Drop use of SCLK_MAC_PLL

The SCLK_MAC_PLL id is not exported or referenced upstream. It is also
not referenced in vendor U-Boot or vendor kernel 4.4, 4.19, 5.10 or 6.1.

Relax the check for parent id SCLK_MAC_PLL when using internal clock
source for gmac to allow use of clock/rk3288-cru.h from dts/upstream.

All in-tree and upstream rk3288 DTs use an external clock as parent,
so no functional change to boards is expected with this change.

Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>