ath11k: Do not put HW in DBS mode for WCN6750

Though WCN6750 is a single PDEV device, it is not a
DBS solution. So, do not put HW in DBS mode for WCN6750.

Tested-on: WCN6750 hw1.0 AHB WLAN.MSL.1.0.1-00573-QCAMSLSWPLZ-1
Tested-on: WCN6855 hw2.0 PCI WLAN.HSP.1.1-01720.1-QCAHSPSWPL_V1_V2_SILICONZ_LITE-1
Tested-on: QCN9074 hw1.0 PCI WLAN.HK.2.5.0.1-01100-QCAHKSWPL_SILICONZ-1
Tested-on: IPQ8074 hw2.0 AHB WLAN.HK.2.4.0.1-00192-QCAHKSWPL_SILICONZ-1

Signed-off-by: Manikanta Pubbisetty <quic_mpubbise@quicinc.com>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://lore.kernel.org/r/20220406094107.17878-10-quic_mpubbise@quicinc.com