ath10k: add missing braces to ath10k_pci_tx_pipe_cleanup

The indentation here implies this was meant to be
a multi-statement if, but it lacks the braces.

kvalo: add "ath10k: " prefix

Signed-off-by: Dave Jones <davej@fedoraproject.org>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>