qcacmn: spectral: Fix misspelling of 'frequency'

Address the following issue in wlan_spectral_utils_api.h:
CHECK: 'frequncy' may be misspelled - perhaps 'frequency'?

Change-Id: Ie9675796d12feded20d968d09c439f2e6ac5c9f0
CRs-Fixed: 2241582

spectral/dispatcher/inc/wlan_spectral_utils_api.h

@@ -98,7 +98,7 @@ struct spectral_legacy_cbacks {
 int16_t spectral_vdev_get_chan_freq(struct wlan_objmgr_vdev *vdev);
 
 /**
- * spectral_vdev_get_sec20chan_freq_mhz - Get vdev secondary channel frequncy
+ * spectral_vdev_get_sec20chan_freq_mhz - Get vdev secondary channel frequency
  * @vdev:   vdev object
  * @sec20chan_freq: secondary channel frequency
  *