The tasklet is an old API that should be deprecated, usually can be
converted to another decent API.  This patch replaces the usage of
tasklet in pcsp driver with a simple work.  In pcsp driver, a global
tasklet is used for offloading the period-elapse handling in the
hrtimer callback (introduced in commit 96c7d478 "ALSA: pcsp - Fix
locking messes in snd-pcsp").  It can be achieved gracefully with a
work queued in the high-prio system workqueue.

This also changes tasklet_kill() with cancel_work_sync() in the
sync_stop callback, which is anyway better to assure canceling the
pending tasks.

Link: https://lore.kernel.org/r/20200903104131.21097-2-tiwai@suse.deSigned-off-by: Takashi Iwai <tiwai@suse.de>