jack: implement pcm operation sw_params

jack: implement pcm operation sw_params

Alsa-lib commit 88e4ae27 introduced a dynamic recalculation of the avail_min
value on the underlaying slave devices.
This updated avail_min value is not reaching the alsa-jack plugin due to lack
of the sw_params operation.
This patch adds this missing operation to correctly apply an updated avail_min
setting during runtime.

Fixes: https://github.com/alsa-project/alsa-plugins/pull/43
Signed-off-by: Andreas Pape <apape@de.adit-jv.com>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>