wifi: ath12k: use ATH12K_PCI_IRQ_DP_OFFSET for DP IRQ

Like ATH12K_PCI_IRQ_CE0_OFFSET, define ATH12K_PCI_IRQ_DP_OFFSET for
DP to save the IRQ instead of base_vector from MSI config.

Tested-on: WCN7850 hw2.0 PCI WLAN.HMT.1.0-03427-QCAHMTSWPL_V1.0_V2.0_SILICONZ-1.15378.4

Signed-off-by: Kang Yang <quic_kangyang@quicinc.com>
Acked-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://lore.kernel.org/r/20231121021304.12966-4-quic_kangyang@quicinc.com