net: cdc_ncm: cleanup a type issue in cdc_ncm_setup()

This is harmless but cdc_ncm_setup() returns negative error codes
truncated to u8 values.  There is only one caller and treats all
non-zero returns as errors but doesn't store the the return code.  So
the code works correctly but it's messy and upsets the static checkers.
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/usb/cdc_ncm.c

@@ -66,7 +66,7 @@ static void cdc_ncm_tx_timeout_start(struct cdc_ncm_ctx *ctx);
 static enum hrtimer_restart cdc_ncm_tx_timer_cb(struct hrtimer *hr_timer);
 static struct usb_driver cdc_ncm_driver;
 
-static u8 cdc_ncm_setup(struct usbnet *dev)
+static int cdc_ncm_setup(struct usbnet *dev)
 {
 	struct cdc_ncm_ctx *ctx = (struct cdc_ncm_ctx *)dev->data[0];
 	struct usb_cdc_ncm_ntb_parameters ncm_parm;