ath11k: add hw reg support for WCN6855

Reg address of WCN6855 is different from other devices,
so add separate reg definition for this target.

Tested-on: WCN6855 hw2.0 PCI WLAN.HSP.1.1-01720.1-QCAHSPSWPL_V1_V2_SILICONZ_LITE-1

Signed-off-by: Govind Singh <govinds@codeaurora.org>
Signed-off-by: Baochen Qiang <bqiang@codeaurora.org>
Signed-off-by: Jouni Malinen <jouni@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20210511162214.29475-2-jouni@codeaurora.org