USB: storage: ums-realtek: fix error code in rts51x_read_mem()

The rts51x_read_mem() function should return negative error codes.
Currently if the kmalloc() fails it returns USB_STOR_TRANSPORT_ERROR (3)
which is treated as success by the callers.

Fixes: 065e609 ("ums_realtek: do not use stack memory for DMA")
Acked-by: Alan Stern <[email protected]>
Signed-off-by: Dan Carpenter <[email protected]>
Link: https://lore.kernel.org/r/20220304073504.GA26464@kili
Signed-off-by: Greg Kroah-Hartman <[email protected]>

drivers/usb/storage/realtek_cr.c

@@ -365,7 +365,7 @@ static int rts51x_read_mem(struct us_data *us, u16 addr, u8 *data, u16 len)
 
 	buf = kmalloc(len, GFP_NOIO);
 	if (buf == NULL)
-		return USB_STOR_TRANSPORT_ERROR;
+		return -ENOMEM;
 
 	usb_stor_dbg(us, "addr = 0x%x, len = %d\n", addr, len);