dt-bindings: soc: fsl: cpm_qe: cpm1-tsa: Remove unneeded property

Remove the unneeded and unused #fsl,serial-cells property.

Signed-off-by: Herve Codina <herve.codina@bootlin.com>
Link: https://lore.kernel.org/r/20230307141503.159766-3-herve.codina@bootlin.com


Signed-off-by: Mark Brown <broonie@kernel.org>