free(9) sizes for USB ifaces

[Martin Pieuchot]

We already have the number of available interfaces in the configuration
descriptor, so use it to free the array.

ok?

Index: usb_subr.c
===================================================================
RCS file: /cvs/src/sys/dev/usb/usb_subr.c,v
retrieving revision 1.140
diff -u -p -r1.140 usb_subr.c
--- usb_subr.c  14 Nov 2018 17:00:33 -0000      1.140
+++ usb_subr.c  14 Nov 2018 17:27:26 -0000
@@ -648,7 +648,7 @@ usbd_set_config_index(struct usbd_device
                nifc = dev->cdesc->bNumInterface;
                for (ifcidx = 0; ifcidx < nifc; ifcidx++)
                        usbd_free_iface_data(dev, ifcidx);
-               free(dev->ifaces, M_USB, 0);
+               free(dev->ifaces, M_USB, nifc * sizeof(*dev->ifaces));
                free(dev->cdesc, M_USB, UGETW(dev->cdesc->wTotalLength));
                dev->ifaces = NULL;
                dev->cdesc = NULL;
@@ -775,8 +775,8 @@ usbd_set_config_index(struct usbd_device
 
        /* Allocate and fill interface data. */
        nifc = cdp->bNumInterface;
-       dev->ifaces = mallocarray(nifc, sizeof(struct usbd_interface),
-           M_USB, M_NOWAIT | M_ZERO);
+       dev->ifaces = mallocarray(nifc, sizeof(*dev->ifaces), M_USB,
+           M_NOWAIT | M_ZERO);
        if (dev->ifaces == NULL) {
                err = USBD_NOMEM;
                goto bad;
@@ -1406,7 +1406,7 @@ usb_free_device(struct usbd_device *dev)
                nifc = dev->cdesc->bNumInterface;
                for (ifcidx = 0; ifcidx < nifc; ifcidx++)
                        usbd_free_iface_data(dev, ifcidx);
-               free(dev->ifaces, M_USB, 0);
+               free(dev->ifaces, M_USB, nifc * sizeof(*dev->ifaces));
        }
        if (dev->cdesc != NULL)
                free(dev->cdesc, M_USB, UGETW(dev->cdesc->wTotalLength));