staging: rtl8723bs: Remove set but not used variable 'tmp_aid'

Fixes gcc '-Wunused-but-set-variable' warning:

drivers/staging/rtl8723bs/core/rtw_sta_mgt.c: In function rtw_alloc_stainfo:
drivers/staging/rtl8723bs/core/rtw_sta_mgt.c:190:7: warning: variable tmp_aid set but not used [-Wunused-but-set-variable]

It is not used since commit 554c0a3a ("staging:
Add rtl8723bs sdio wifi driver")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: zhengbin <zhengbin13@huawei.com>
Link: https://lore.kernel.org/r/1570352999-45790-3-git-send-email-zhengbin13@huawei.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/rtl8723bs/core/rtw_sta_mgt.c

@@ -187,7 +187,6 @@ u32 _rtw_free_sta_priv(struct	sta_priv *pstapriv)
 /* struct	sta_info *rtw_alloc_stainfo(_queue *pfree_sta_queue, unsigned char *hwaddr) */
 struct	sta_info *rtw_alloc_stainfo(struct	sta_priv *pstapriv, u8 *hwaddr)
 {
-	uint tmp_aid;
 	s32	index;
 	struct list_head	*phash_list;
 	struct sta_info *psta;
@@ -211,8 +210,6 @@ struct	sta_info *rtw_alloc_stainfo(struct	sta_priv *pstapriv, u8 *hwaddr)
 
 		/* spin_unlock_bh(&(pfree_sta_queue->lock)); */
 
-		tmp_aid = psta->aid;
-
 		_rtw_init_stainfo(psta);
 
 		psta->padapter = pstapriv->padapter;