wifi: ath12k: Do not use scan_flags from struct ath12k_wmi_scan_req_arg

As discussed in [1] to fix the mismatch between the WMI_SCAN_XXX macros &
their corresponding scan_f_xxx bitfield equivalent, lets stop using the
scan_flags in the union altogether.

[1] https://lore.kernel.org/all/4be7d62e-cb59-462d-aac2-94e27efc22ff@quicinc.com/



Tested-on: QCN9274 hw2.0 PCI CI_WLAN.WBE.1.3-02907.1-QCAHKSWPL_SILICONZ-10

Signed-off-by: Nicolas Escande <nico.escande@gmail.com>
Acked-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://msgid.link/20240211145548.1939610-2-nico.escande@gmail.com