clk: imx: drop imx_unregister_clocks

There is no user using imx_unregister_clocks, so drop it.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
Reviewed-by: Stephen Boyd <sboyd@kernel.org>
Link: https://lore.kernel.org/r/20230506090856.3599035-1-peng.fan@oss.nxp.com


Signed-off-by: Abel Vesa <abel.vesa@linaro.org>