hw/block/fdc: Declare shared prototypes in fdc-internal.h

hw/block/fdc: Declare shared prototypes in fdc-internal.h

We want to extract ISA/SysBus code from the generic fdc.c file.
First, declare the prototypes we will access from the new units
into a new local header: "fdc-internal.h".

Acked-by: Mark Cave-Ayland <[email protected]>
Reviewed-by: Mark Cave-Ayland <[email protected]>
Acked-by: Paolo Bonzini <[email protected]>
Signed-off-by: Philippe Mathieu-Daudé <[email protected]>
Message-id: 20210614193220.2007159[email protected]
Signed-off-by: John Snow <[email protected]>