wifi: ath11k: add support to configure channel dwell time

Add support to configure channel dwell time during scan.
Dwell time help to stay on the channel for a specified duration
during scan and aid userspace in finding WiFi networks. Very
useful in passive scans where longer dwell times are needed
to find the WiFi networks.

Configure channel dwell time from duration of the scan request
received from mac80211 when the duration is non-zero. When the
scan request does not have duration value, use the default ones,
the current implementation.

Advertise corresponding feature flag NL80211_EXT_FEATURE_SET_SCAN_DWELL
to enable the feature.

Change is applicable for all ath11k hardware.

Tested-on: WCN6750 hw1.0 AHB WLAN.MSL.1.0.1-00887-QCAMSLSWPLZ-1

Signed-off-by: Manikanta Pubbisetty <quic_mpubbise@quicinc.com>
Reviewed-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://lore.kernel.org/r/20221007051130.6067-1-quic_mpubbise@quicinc.com