staging: r8188eu: make xmitframe_swencrypt a void function

xmitframe_swencrypt always returns _SUCCESS and the caller does not check
the return value. We can remove the return value and make
xmitframe_swencrypt a void function.
Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Tested-by: Philipp Hortmann <philipp.g.hortmann@gmail.com> # Edimax N150
Link: https://lore.kernel.org/r/20221230180646.91008-2-martin@kaiser.cxSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/r8188eu/core/rtw_xmit.c

@@ -761,7 +761,7 @@ static s32 xmitframe_addmic(struct adapter *padapter, struct xmit_frame *pxmitfr
 	return _SUCCESS;
 }
 
-static s32 xmitframe_swencrypt(struct adapter *padapter, struct xmit_frame *pxmitframe)
+static void xmitframe_swencrypt(struct adapter *padapter, struct xmit_frame *pxmitframe)
 {
 	struct	pkt_attrib	 *pattrib = &pxmitframe->attrib;
 
@@ -781,8 +781,6 @@ static s32 xmitframe_swencrypt(struct adapter *padapter, struct xmit_frame *pxmi
 			break;
 		}
 	}
-
-	return _SUCCESS;
 }
 
 s32 rtw_make_wlanhdr(struct adapter *padapter, u8 *hdr, struct pkt_attrib *pattrib)