wifi: ath12k: Rename hw.c to Wi-Fi 7 specific implementation file

wifi: ath12k: Rename hw.c to Wi-Fi 7 specific implementation file

Rename hw.c to hw_wifi7.c to reflect its focus on Wi-Fi 7 chipset
specific configurations. Clarify the files role in containing
hardware dependent logic tailored to the Wi-Fi 7 family.

This change is part of a broader effort to modularize the codebase
by separating common and target specific components into distinct
modules for improved clarity and maintainability.

Tested-on: QCN9274 hw2.0 PCI WLAN.WBE.1.3.1-00173-QCAHKSWPL_SILICONZ-1
Tested-on: WCN7850 hw2.0 PCI WLAN.HMT.1.0.c5-00481-QCAHMTSWPL_V1.0_V2.0_SILICONZ-3

Signed-off-by: Kiran Venkatappa <quic_kiranv@quicinc.com>
Reviewed-by: Vasanthakumar Thiagarajan <vasanthakumar.thiagarajan@oss.qualcomm.com>
Reviewed-by: Baochen Qiang <baochen.qiang@oss.qualcomm.com>
Link: https://patch.msgid.link/20250812-ath12k-mod-v1-5-8c9b0eb9335d@quicinc.com
Signed-off-by: Jeff Johnson <jeff.johnson@oss.qualcomm.com>