staging: r8188eu: Cocci spatch "noderef"

sizeof when applied to a pointer typed expression gives the size of the
pointer.
Found by coccinelle spatch "misc/noderef.cocci"
Signed-off-by: Thomas Meyer <thomas@m3y3r.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/rtl8188eu/os_dep/ioctl_linux.c

@@ -6973,7 +6973,7 @@ static int rtw_mp_ctx(struct net_device *dev,
 	stop = strncmp(extra, "stop", 4);
 	sscanf(extra, "count =%d, pkt", &count);
 
-	_rtw_memset(extra, '\0', sizeof(extra));
+	_rtw_memset(extra, '\0', sizeof(*extra));
 
 	if (stop == 0) {
 		bStartTest = 0; /*  To set Stop */