wifi: ath11k: add support default regdb while searching board-2.bin for WCN6855

Sometimes board-2.bin does not have the regdb data which matched the
parameters such as vendor, device, subsystem-vendor, subsystem-device
and etc. Add default regdb data with 'bus=%s' into board-2.bin for
WCN6855, then ath11k use 'bus=pci' to search regdb data in board-2.bin
for WCN6855.

kernel: [  122.515808] ath11k_pci 0000:03:00.0: boot using board name 'bus=pci,vendor=17cb,device=1103,subsystem-vendor=17cb,subsystem-device=3374,qmi-chip-id=2,qmi-board-id=262'
kernel: [  122.517240] ath11k_pci 0000:03:00.0: boot firmware request ath11k/WCN6855/hw2.0/board-2.bin size 6179564
kernel: [  122.517280] ath11k_pci 0000:03:00.0: failed to fetch regdb data for bus=pci,vendor=17cb,device=1103,subsystem-vendor=17cb,subsystem-device=3374,qmi-chip-id=2,qmi-board-id=262 from ath11k/WCN6855/hw2.0/board-2.bin
kernel: [  122.517464] ath11k_pci 0000:03:00.0: boot using board name 'bus=pci'
kernel: [  122.518901] ath11k_pci 0000:03:00.0: boot firmware request ath11k/WCN6855/hw2.0/board-2.bin size 6179564
kernel: [  122.518915] ath11k_pci 0000:03:00.0: board name
kernel: [  122.518917] ath11k_pci 0000:03:00.0: 00000000: 62 75 73 3d 70 63 69                             bus=pci
kernel: [  122.518918] ath11k_pci 0000:03:00.0: boot found match regdb data for name 'bus=pci'
kernel: [  122.518920] ath11k_pci 0000:03:00.0: boot found regdb data for 'bus=pci'
kernel: [  122.518921] ath11k_pci 0000:03:00.0: fetched regdb

Tested-on: WCN6855 hw2.0 PCI WLAN.HSP.1.1-03125-QCAHSPSWPL_V1_V2_SILICONZ_LITE-3

Signed-off-by: Wen Gong <quic_wgong@quicinc.com>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://lore.kernel.org/r/20230517133959.8224-1-quic_wgong@quicinc.com