staging: r8188eu: fix a potential memory leak in rtw_init_cmd_priv()

In rtw_init_cmd_priv(), if `pcmdpriv->rsp_allocated_buf` is allocated
in failure, then `pcmdpriv->cmd_allocated_buf` will not be properly
released. Besides, considering there are only two error paths and the
first one can directly return, we do not need to implicitly jump to the
`exit` tag to execute the error handling code.

So this patch added `kfree(pcmdpriv->cmd_allocated_buf);` on the error
path to release the resource and simplified the return logic of
rtw_init_cmd_priv(). As there is no proper device to test with, no
runtime testing was performed.

Tested-by: Philipp Hortmann <philipp.g.hortmann@gmail.com> # Edimax N150
Signed-off-by: Xiaoke Wang <xkernel.wang@foxmail.com>
Link: https://lore.kernel.org/r/tencent_1B6AAE10471D4556788892F8FF3E4812F306@qq.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/r8188eu/core/rtw_cmd.c

@@ -57,8 +57,6 @@ static int _rtw_enqueue_cmd(struct __queue *queue, struct cmd_obj *obj)
 
 u32	rtw_init_cmd_priv(struct cmd_priv *pcmdpriv)
 {
-	u32 res = _SUCCESS;
-
 	init_completion(&pcmdpriv->enqueue_cmd);
 	/* sema_init(&(pcmdpriv->cmd_done_sema), 0); */
 	init_completion(&pcmdpriv->start_cmd_thread);
@@ -73,27 +71,24 @@ u32	rtw_init_cmd_priv(struct cmd_priv *pcmdpriv)
 	pcmdpriv->cmd_allocated_buf = kzalloc(MAX_CMDSZ + CMDBUFF_ALIGN_SZ,
 					      GFP_KERNEL);
 
-	if (!pcmdpriv->cmd_allocated_buf) {
-		res = _FAIL;
-		goto exit;
-	}
+	if (!pcmdpriv->cmd_allocated_buf)
+		return _FAIL;
 
 	pcmdpriv->cmd_buf = pcmdpriv->cmd_allocated_buf  +  CMDBUFF_ALIGN_SZ - ((size_t)(pcmdpriv->cmd_allocated_buf) & (CMDBUFF_ALIGN_SZ - 1));
 
 	pcmdpriv->rsp_allocated_buf = kzalloc(MAX_RSPSZ + 4, GFP_KERNEL);
 
 	if (!pcmdpriv->rsp_allocated_buf) {
-		res = _FAIL;
-		goto exit;
+		kfree(pcmdpriv->cmd_allocated_buf);
+		return _FAIL;
 	}
 
 	pcmdpriv->rsp_buf = pcmdpriv->rsp_allocated_buf  +  4 - ((size_t)(pcmdpriv->rsp_allocated_buf) & 3);
 
 	pcmdpriv->cmd_done_cnt = 0;
 	pcmdpriv->rsp_cnt = 0;
-exit:
 
-	return res;
+	return _SUCCESS;
 }
 
 u32 rtw_init_evt_priv(struct evt_priv *pevtpriv)