wifi: ath12k: avoid repeated wiphy access from hw

Currently repeated access of wiphy data from mac80211 hw structure is
happen inside the mac80211 registration helper functions. So optimize
these helper functions by storing wiphy data locally and accessing it
directly.

Tested-on: QCN9274 hw2.0 PCI WLAN.WBE.1.0.1-00029-QCAHKSWPL_SILICONZ-1

Signed-off-by: Karthikeyan Periyasamy <quic_periyasa@quicinc.com>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://lore.kernel.org/r/20231201013735.2292313-1-quic_periyasa@quicinc.com