qcacmn: Fix the nss geting from tlv being invalid in 11b mode

Only in 11b mode, exclusive of other legacy modes(11ag) will
the NSS obtained from the TLV header be invalid, which is 0
and cannot be resolved. This change will set nss to 1 in 11b.

Change-Id: I93e8bdb125764fb0247265da328929ecc837fb84
CRs-Fixed: 3275793

dp/inc/cdp_txrx_cmn.h

@@ -139,7 +139,7 @@ enum {
 };
 
 /*
- * BW types of used for RX PPDU
+ * BW types used for RX PPDU
  */
 enum rx_tlv_bw {
 	RX_TLV_BW_20MHZ,