soc: fsl: cpm1: qmc: Introduce is_tsa_64rxtx flag

In order to support runtime timeslot route changes, some operations will
be different according the routing table used (common Rx and Tx table or
one table for Rx and one for Tx).

The is_tsa_64rxtx flag is introduced to avoid extra computation to
determine the table format each time we need it.
It is set once at initialization.

Signed-off-by: Herve Codina <herve.codina@bootlin.com>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Link: https://lore.kernel.org/r/20231205152116.122512-15-herve.codina@bootlin.com