ath10k: fix debugfs pktlog_filter write

It is observed that, we are disabling the packet log if we write same
value to the pktlog_filter for the second time. Always enable pktlogs
on non zero filter.

Fixes: 90174455 ("ath10k: add support to configure pktlog filter")
Cc: stable@vger.kernel.org
Signed-off-by: Anilkumar Kolli <akolli@qti.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>