floppy: use symbolic register names in the sparc32 port

The sparc port used to be forced to rely on numeric register indexes
with their equivalent in comments. Now that they don't depend on the
IO port we can use their symbolic names.

Link: https://lore.kernel.org/r/20200331094054.24441-7-w@1wt.eu


Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Denis Efremov <efremov@linux.com>