fdc-test: introduced qtest no_media_on_start and cmos qtest for floppy

As default a guest has always one floppy drive so 0x10 byte in CMOS
has to have 0x40 value. Higher 4 bits means that the first floppy drive
is 1.44 Mb 3"5 drive and lower 4 bits means the second drive is not present.

After the guest starts DSKCHG bit in DIR register should be set. If there
is no media in drive, this bit should be set all the time.

Because we start the guest without media in drive, we have to swap
'eject' and 'change' in 'test_media_change'.

Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>