floppy: use symbolic register names in the powerpc port

Now we can use FD_STATUS and FD_DATA instead of 4 or 5, let's do
this, and also use STATUS_DMA and STATUS_READY for the status bits.

Link: https://lore.kernel.org/r/20200331094054.24441-6-w@1wt.eu
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Denis Efremov <efremov@linux.com>

arch/powerpc/include/asm/floppy.h

@@ -61,21 +61,22 @@ static irqreturn_t floppy_hardint(int irq, void *dev_id)
 	st = 1;
 	for (lcount=virtual_dma_count, lptr=virtual_dma_addr;
 	     lcount; lcount--, lptr++) {
-		st=inb(virtual_dma_port+4) & 0xa0 ;
-		if (st != 0xa0)
+		st = inb(virtual_dma_port + FD_STATUS);
+		st &= STATUS_DMA | STATUS_READY;
+		if (st != (STATUS_DMA | STATUS_READY))
 			break;
 		if (virtual_dma_mode)
-			outb_p(*lptr, virtual_dma_port+5);
+			outb_p(*lptr, virtual_dma_port + FD_DATA);
 		else
-			*lptr = inb_p(virtual_dma_port+5);
+			*lptr = inb_p(virtual_dma_port + FD_DATA);
 	}
 	virtual_dma_count = lcount;
 	virtual_dma_addr = lptr;
-	st = inb(virtual_dma_port+4);
+	st = inb(virtual_dma_port + FD_STATUS);
 
-	if (st == 0x20)
+	if (st == STATUS_DMA)
 		return IRQ_HANDLED;
-	if (!(st & 0x20)) {
+	if (!(st & STATUS_DMA)) {
 		virtual_dma_residue += virtual_dma_count;
 		virtual_dma_count=0;
 		doing_vdma = 0;