[SPARC]: Fix floppy on some sun4c systems.

Add in code to support an 82077 FDC on sun4c systems. There is a
problem with spurious interrupts but it does apear to work.

Testing on my SS2 (82072A FDC) shows that the floppy driver is not
100% with sun4c any way (any spurious interrupt kills it, requiring a
reboot to recover).

Signed-off-by: Mark Fortescue <mark@mtfhpc.demon.co.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>