qcacld-3.0: Do memzero of htt_frag_desc inside HELIUMPLUS flag

Do memzero of htt_frag_desc inside HELIUMPLUS flag as
htt_frag_desc is defined only for HELIUMPLUS.

Change-Id: Ie738881c5330956b24376f145f03dd977bf88f7b
CRs-Fixed: 2096935

core/dp/txrx/ol_tx.c

@@ -556,7 +556,10 @@ ol_tx_prepare_ll_fast(struct ol_txrx_pdev_t *pdev,
 	}
 
 	htt_tx_desc = tx_desc->htt_tx_desc;
+
+#if defined(HELIUMPLUS)
 	qdf_mem_zero(tx_desc->htt_frag_desc, sizeof(struct msdu_ext_desc_t));
+#endif
 
 	/* Make sure frags num is set to 0 */
 	/*