Fix "-d unimp" trace results:

  Unknown QEMU_IFLA_BRPORT type 35
  Unknown QEMU_IFLA_BRPORT type 36

Also process IFLA_EXT_MASK to fix:

  Unknown target QEMU_IFLA type: 29

Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <20201117111905.843925-1-laurent@vivier.eu>