wifi: ath12k: fix rmmod/modprobe cycle after qmi failure

Currently, the core panic notifier is not being released and the debugfs
directory is not being removed, which causes issues during the
rmmod/modprobe cycle after a QMI failure. Fix this by releasing the core
panic notifier and removing the debugfs directory in the cleanup path.

Signed-off-by: Raj Kumar Bhagat <quic_rajkbhag@quicinc.com>
Signed-off-by: Jeff Johnson <jeff.johnson@oss.qualcomm.com>