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: NWilly Tarreau <w@1wt.eu>
Signed-off-by: NDenis Efremov <efremov@linux.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

arch/arm/include/asm/floppy.h

@@ -50,17 +50,13 @@ static inline int fd_dma_setup(void *data, unsigned int length,
  * to a non-zero track, and then restoring it to track 0.  If an error occurs,
  * then there is no floppy drive present.       [to be put back in again]
  */
-static unsigned char floppy_selects[2][4] =
-{
-	{ 0x10, 0x21, 0x23, 0x33 },
-	{ 0x10, 0x21, 0x23, 0x33 }
-};
+static unsigned char floppy_selects[4] = { 0x10, 0x21, 0x23, 0x33 };
 
 #define fd_setdor(dor)								\
 do {										\
 	int new_dor = (dor);							\
 	if (new_dor & 0xf0)							\
-		new_dor = (new_dor & 0x0c) | floppy_selects[fdc][new_dor & 3];	\
+		new_dor = (new_dor & 0x0c) | floppy_selects[new_dor & 3];	\
 	else									\
 		new_dor &= 0x0c;						\
 	outb(new_dor, FD_DOR);							\
@@ -84,9 +80,7 @@ do {										\
  */
 static void driveswap(int *ints, int dummy, int dummy2)
 {
-	floppy_selects[0][0] ^= floppy_selects[0][1];
-	floppy_selects[0][1] ^= floppy_selects[0][0];
-	floppy_selects[0][0] ^= floppy_selects[0][1];
+	swap(floppy_selects[0], floppy_selects[1]);
 }
 
 #define EXTRA_FLOPPY_PARAMS ,{ "driveswap", &driveswap, NULL, 0, 0 }