hw/usb/hcd-ehci-sysbus: Free USBPacket on instance finalize()

hw/usb/hcd-ehci-sysbus: Free USBPacket on instance finalize()

When building with --enable-sanitizers we get:

  Direct leak of 32 byte(s) in 2 object(s) allocated from:
      #0 0x5618479ec7cf in malloc (qemu-system-aarch64+0x233b7cf)
      #1 0x7f675745f958 in g_malloc (/lib64/libglib-2.0.so.0+0x58958)
      #2 0x561847f02ca2 in usb_packet_init hw/usb/core.c:531:5
      #3 0x561848df4df4 in usb_ehci_init hw/usb/hcd-ehci.c:2575:5
      #4 0x561847c119ac in ehci_sysbus_init hw/usb/hcd-ehci-sysbus.c:73:5
      #5 0x56184a5bdab8 in object_init_with_type qom/object.c:375:9
      #6 0x56184a5bd955 in object_init_with_type qom/object.c:371:9
      #7 0x56184a5a2bda in object_initialize_with_type qom/object.c:517:5
      #8 0x56184a5a24d5 in object_initialize qom/object.c:536:5
      #9 0x56184a5a2f6c in object_initialize_child_with_propsv qom/object.c:566:5
      #10 0x56184a5a2e60 in object_initialize_child_with_props qom/object.c:549:10
      #11 0x56184a5a3a1e in object_initialize_child_internal qom/object.c:603:5
      #12 0x561849542d18 in npcm7xx_init hw/arm/npcm7xx.c:427:5

Similarly to commit d710e1e7bd3 ("usb: ehci: fix memory leak in
ehci"), fix by calling usb_ehci_finalize() to free the USBPacket.

Fixes: 7341ea075c0
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20210323183701.281152-1-f4bug@amsat.org>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>