The current logic for initializing arvif is present in both the add
interface operation callback and ath12k_mac_assign_link_vif(). The former
handles deflink initialization, while the latter is responsible for other
links. This redundancy could be avoided by using a common helper function.
Hence, add a new helper ath12k_mac_init_arvif() which initializes a
given arvif.
Since synchronizing rcu is not required after adding a rcu pointer, remove
that now.
Tested-on: QCN9274 hw2.0 PCI WLAN.WBE.1.3.1-00173-QCAHKSWPL_SILICONZ-1
Signed-off-by: Aditya Kumar Singh <aditya.kumar.singh@xxxxxxxxxxxxxxxx>