ath11k: set TxBf parameters after vdev start

The channel info parameters are required by the firmware to process TxBf
parameters. Currently TxBf is passed prior to the channel info. This patch
moves TxBf setup after the channel setup.

Signed-off-by: John Crispin <john@phrozen.org>
Signed-off-by: Bhagavathi Perumal S <bperumal@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>