qcacmn: Do not prohibit aspectral if DFS is NULL

Bring up a 5GHZ AP on HKV2 board and enable agile spectral scan
using "athssd -i wifi0 -j ath0 -a -f 5180" cmd. Agile spectral
scan fails to begin.

Agile spectral scan must not begin if RCAC is enabled as both cannot
run simultaneously. All the pdevs of the current PSOC are passed as an
input to 'target_if_is_aspectral_prohibited_by_adfs' to validate if
rcac is enabled on any of them. In case of HKV2, both 2G/5G PDEVs belong
to the same PSOC, when 2G PDEV is given as input, ucfg_dfs_get_rcac_enable
returns a failure as DFS is NULL.
Hence target_if_is_aspectral_prohibited_by_adfs returns a failure and
agile scan does not begin.

RCAC feature is only for 5GHZ channels and need not be validated for
2G PDEV. Hence do not block aspectral scan if DFS is NULL for 2G PDEV.

CRs-Fixed: 2947887
Change-Id: Icce2300f7ca2a4caf7d46cc23fe055f07f90266c

umac/dfs/dispatcher/src/wlan_dfs_ucfg_api.c

@@ -474,6 +474,11 @@ QDF_STATUS ucfg_dfs_get_rcac_enable(struct wlan_objmgr_pdev *pdev,
 {
 	struct wlan_dfs *dfs;
 
+	if (!tgt_dfs_is_pdev_5ghz(pdev)) {
+		*rcac_en = false;
+		return QDF_STATUS_SUCCESS;
+	}
+
 	dfs = wlan_pdev_get_dfs_obj(pdev);
 	if (!dfs) {
 		dfs_err(dfs, WLAN_DEBUG_DFS_ALWAYS, "null dfs");