wifi: ath12k: Fix scan initiation failure handling

wifi: ath12k: Fix scan initiation failure handling

During a code review, it is observed that in the scenario
where scan initiation fails, the current code schedules the
ar->scan.timeout workqueue which is not necessary.

In the scan initiation failure scenario, exit the code instead
of scheduling the ar->scan.timeout workqueue.

Compile tested only.

Signed-off-by: Vignesh C <quic_vignc@quicinc.com>
Link: https://patch.msgid.link/20250512065849.2833232-1-quic_vignc@quicinc.com
Signed-off-by: Jeff Johnson <jeff.johnson@oss.qualcomm.com>