Drop the incoming_expected global variable

Test against RSTATE_IN_MIGRATE instead.

Please, note that the RSTATE_IN_MIGRATE state is only set when all the
initial VM setup is done, while 'incoming_expected' was set right in
the beginning when parsing command-line options. Shouldn't be a problem
as far as I could check.

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
