ide/atapi: Mark non-data commands as complete

When the command completion code in IDE and AHCI
was unified to put all command completion inside
of a callback, "cmd_done," we neglected to
ensure that all AHCI/ATAPI command paths would
eventually register as finished. for the PCI
interface to IDE this is not a problem because
cmd_done is a nop, but the AHCI implementation
needs to send a D2H_REG_FIS and interrupt back
to the guest to inform of completion.

This patch adds calls to ide_stop_transfer,
which calls ide_cmd_done, inside of
ide_atapi_cmd_ok and ide_atapi_cmd_error.

This fixes regressions observed by trying to boot QEMU
with a Fedora 20 live CD under Q35/AHCI, which uses
ATAPI command 0x00, which is a status check that may
cause a hang because we never complete, and ATAPI
command 0x56, which is unsupported by our current
implementation and results in an error that we never
report back to the guest.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
