clk: gxbb: fix CLKID_ETH defined twice

CLKID_ETH is define in the dt-bindings but has not be commented out in the
clock driver. Just do it now.

Fixes: 738f66d3

 ("clk: gxbb: add AmLogic GXBB clk controller driver")
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Acked-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>