net: stmmac: dwmac-rk: Fix clk rate when provided by soc

net: stmmac: dwmac-rk: Fix clk rate when provided by soc

The first iteration of the dwmac-rk support did access an intermediate
clock directly below the pll selector. This was removed in a subsequent
revision, but the clock and one invocation remained. This results in
the driver trying to set the rate of a non-existent clock when the soc
and not some external source provides the phy clock for RMII phys.

So set the rate of the correct clock and remove the remaining now
completely unused definition.

Fixes: 436f5ae08f9d ("GMAC: add driver for Rockchip RK3288 SoCs integrated GMAC")
Cc: stable@vger.kernel.org
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: David S. Miller <davem@davemloft.net>