Currently the jackpoll_ms option value is passed indirectly by
referring to an array in chip->jackpoll_ms although each card needs to
see only the assigned value.  Also, the sanity check is done at each
time in get_jackpoll_interval() although basically jackpoll_ms option
is a read-only, hence we need to evaluate only once at probe time.

This patch is the code simplification about the above points: the jack
polling interval is directly set to chip->jackpoll_interval so that it
can be simply copied to each codec.

No functional change but only code reduction.
Signed-off-by: Takashi Iwai <tiwai@suse.de>