soc: fsl: cpm1: qmc: Remove timeslots handling from setup_chan()

Timeslots setting is done at channel start() and stop().
There is no more need to do that during setup_chan().

Simply remove timeslot setting from setup_chan().

Signed-off-by: Herve Codina <herve.codina@bootlin.com>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Link: https://lore.kernel.org/r/20231205152116.122512-17-herve.codina@bootlin.com