checkpatch: add hwaddr to @typeList

The script doesn't know about all possible types and learn them as
it parses the code. If it reaches a line with a type cast but the
type isn't known yet, it is misinterpreted as an identifier.

For example the following line:

    foo = (hwaddr) -1;

results in the following false-positive to be reported:

ERROR: spaces required around that '-' (ctx:VxV)

Let's add this standard QEMU type to the list of pre-known types.

Signed-off-by: Greg Kurz <groug@kaod.org>
Message-Id: <150538015789.8149.10902725348939486674.stgit@bahia.lan>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>