staging: rtl8188eu: fix usb_submit_urb error handling

usb_read_port prepares a bulk in urb and calls usb_submit_urb to pass the
usb to the usb core. It seems wrong that usb_read_port returns success to
its caller if usb_submit_urb failed with -EPERM.

According to drivers/usb/core/urb.c, usb_submit_urb returns -EPERM when
an urb is resubmitted after being cancelled by usb_kill_urb etc.

The only caller who checks the return value of usb_read_port is
rtw_hal_inirp_init. This function submits the bulk in urbs for the first
time after the netdevice is opened. We'll not receive -EPERM from
usb_submit_urb in this case. The urbs are resubmitted by
read_port_complete, which does not check for errors from usb_read_port.

This driver may kill pending bulk in urbs when the netdevice is closed when
the driver is unloaded or the system goes to sleep. I don't think that this
will interrupt an ongoing netdev open.
Suggested-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Link: https://lore.kernel.org/r/20210620174057.10201-1-martin@kaiser.cxSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/rtl8188eu/os_dep/usb_ops_linux.c

@@ -366,7 +366,6 @@ u32 usb_read_port(struct adapter *adapter, u32 addr, struct recv_buf *precvbuf)
 	struct usb_device *pusbd = pdvobj->pusbdev;
 	int err;
 	unsigned int pipe;
-	u32 ret = _SUCCESS;
 
 	if (adapter->bDriverStopped || adapter->bSurpriseRemoved ||
 	    adapter->pwrctrlpriv.pnp_bstop_trx) {
@@ -403,10 +402,10 @@ u32 usb_read_port(struct adapter *adapter, u32 addr, struct recv_buf *precvbuf)
 			  precvbuf);/* context is precvbuf */
 
 	err = usb_submit_urb(purb, GFP_ATOMIC);
-	if ((err) && (err != (-EPERM)))
-		ret = _FAIL;
+	if (err)
+		return _FAIL;
 
-	return ret;
+	return _SUCCESS;
 }
 
 void rtw_hal_inirp_deinit(struct adapter *padapter)