floppy: use symbolic register names in the x86 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/20200331094054.24441-9-w@1wt.eu
Cc: x86@kernel.org
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Denis Efremov <efremov@linux.com>

arch/x86/include/asm/floppy.h

@@ -77,25 +77,26 @@ 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);
 	}
 
 #ifdef TRACE_FLPY_INT
 	calls++;
 #endif
-	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;
 #ifdef TRACE_FLPY_INT