[ALSA] ymfpci: fix swap_rear for S/PDIF passthrough

This patch fixes incorrect assignment of swap_rear,
which was broken since patch 'ymfpci - make rear channel swap optional'
It removes module_param rear_swap.

Signed-off-by: Glen Masgai <mimosius@gmx.de>
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>