Add a simple register fuzzing test to floppy controller tests.
Signed-off-by: NBlue Swirl <blauwirbel@gmail.com>

If you try to read from a floppy drive without a media, you should get
an abnormal termination error.
Signed-off-by: NPavel Hrdina <phrdina@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

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: NPavel Hrdina <phrdina@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Let's start with testing media change.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NPaolo Bonzini <pbonzini@redhat.com>