staging: r8188eu: remove NULL check before vfree

vfree can handle NULL pointer as its argument.
According to coccinelle isnullfree check, remove NULL check
before vfree operation.
Signed-off-by: Dongliang Mu <mudongliangabcd@gmail.com>
Link: https://lore.kernel.org/r/20220614133239.147076-1-dzm91@hust.edu.cnSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/r8188eu/os_dep/usb_intf.c

@@ -372,7 +372,7 @@ static struct adapter *rtw_usb_if1_init(struct dvobj_priv *dvobj,
 free_adapter:
 	if (pnetdev)
 		rtw_free_netdev(pnetdev);
-	else if (padapter)
+	else
 		vfree(padapter);
 
 	return NULL;