m68k: mac: Revisit floppy disc controller base addresses

Rename floppy_type macros to make them more consistent with the scsi_type
macros, which are named after classes of models with similar memory maps.

The MAC_FLOPPY_OLD symbol is introduced to change the relevant base
address from 0x50F00000 to 0x50000000 (consistent with MAC_SCSI_OLD).

The documentation for LC-class machines has the IO devices at offsets
from $50F00000. Use these addresses for MAC_FLOPPY_LC (consistent with
MAC_SCSI_LC) because they may not be aliased elsewhere in the memory map.

Add comments with controller type information from 'Designing Cards and
Drivers for the Macintosh Family', relevant Developer Notes and
http://mess.redump.net/mess/driver_info/mac_technical_notes



Adopt phys_addr_t to avoid type casts.

Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Tested-by: Stan Johnson <userm57@yahoo.com>
Acked-by: Laurent Vivier <lvivier@redhat.com>
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>