ath11k: Add missing qmi_txn_cancel()

Currently many functions do not follow this guidance when
qmi_send_request() fails, therefore add missing
qmi_txn_cancel() in the qmi_send_request() error path.

Also remove initialization on 'struct qmi_txn'
since qmi_tx_init() performs all necessary initialization.

Tested-on: QCN9074 hw1.0 PCI WLAN.HK.2.4.0.1-01838-QCAHKSWPL_SILICONZ-1

Signed-off-by: Anilkumar Kolli <akolli@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/1635857558-21733-1-git-send-email-akolli@codeaurora.org