floppy: remove incomplete support for second FDC from ARM code

floppy: remove incomplete support for second FDC from ARM code

The ARM code was written with the apparent hope to one day support
a second FDC except that the code was incomplete and only touches
the first one, which is also reflected by N_FDC==1. However this
made its fd_outb() macro artificially depend on the global or local
"fdc" variable.

Let's get rid of this and make it explicit it doesn't rely on this
variable anymore.

Link: https://lore.kernel.org/r/20200301195555.11154-3-w@1wt.eu
Cc: Ian Molton <spyro@f2s.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Denis Efremov <efremov@linux.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>