dt-bindings: clock: imx8mm: don't use multiple blank lines

Avoid the following checkpatch warning:

include/dt-bindings/clock/imx8mm-clock.h:284: check: Please don't use
 multiple blank lines

Signed-off-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
Reviewed-by: Abel Vesa <abel.vesa@linaro.org>
Signed-off-by: Abel Vesa <abel.vesa@linaro.org>
Link: https://lore.kernel.org/r/20220722215445.3548530-13-marcel@ziswiler.com