qcacmn: Restrict Agile Spectral start scan in SBS mode

Ensure that at a time only one Agile Spectral scan is
happening across all the 5G pdevs in SBS mode.

CRs-Fixed: 2517522
Change-Id: If31a4451b82ce1d7d8a46bc604ca91bf4b6dac29

umac/regulatory/dispatcher/src/wlan_reg_services_api.c

@@ -807,6 +807,8 @@ enum band_info wlan_reg_chan_to_band(uint32_t chan_num)
 	return reg_chan_to_band(chan_num);
 }
 
+qdf_export_symbol(wlan_reg_chan_to_band);
+
 /**
  * wlan_reg_get_chan_enum() - Get channel enum for given channel number
  * @chan_num: Channel number