ath11k: put hw to DBS using WMI_PDEV_SET_HW_MODE_CMDID

It's recommended to use wmi command WMI_PDEV_SET_HW_MODE_CMDID to put hardware
to dbs mode instead of wmi_init command. This fixes a few strange stability
issues.

Tested-on: QCA6390 hw2.0 PCI WLAN.HST.1.0.1-01740-QCAHSTSWPLZ_V2_TO_X86-1

Signed-off-by: Carl Huang <cjhuang@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/1607609124-17250-3-git-send-email-kvalo@codeaurora.org