b43: Remove PIO support

Remove b43 PIO support.
DMA works well on all supported devices. There's no reason to use PIO.
Additionally, new devices don't support PIO in hardware anymore.
b43 PIO support is dead and unused code.

After applying this patch please do
git rm drivers/net/wireless/b43/pio.h
git rm drivers/net/wireless/b43/pio.c
to remove the main PIO support code.

Signed-off-by: Michael Buesch <mb@bu3sch.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/b43/dma.c b/drivers/net/wireless/b43/dma.c
index f3552ac..63217b1 100644
--- a/drivers/net/wireless/b43/dma.c
+++ b/drivers/net/wireless/b43/dma.c
@@ -915,11 +915,7 @@
 
 void b43_dma_free(struct b43_wldev *dev)
 {
-	struct b43_dma *dma;
-
-	if (b43_using_pio(dev))
-		return;
-	dma = &dev->dma;
+	struct b43_dma *dma = &dev->dma;
 
 	b43_destroy_dmaring(dma->rx_ring3);
 	dma->rx_ring3 = NULL;
@@ -954,16 +950,11 @@
 
 	err = ssb_dma_set_mask(dev->dev, dmamask);
 	if (err) {
-#ifdef B43_PIO
-		b43warn(dev->wl, "DMA for this device not supported. "
-			"Falling back to PIO\n");
-		dev->__using_pio = 1;
-		return -EAGAIN;
-#else
-		b43err(dev->wl, "DMA for this device not supported and "
-		       "no PIO support compiled in\n");
+		b43err(dev->wl, "The machine/kernel does not support "
+		       "the required DMA mask (0x%08X%08X)\n",
+		       (unsigned int)((dmamask & 0xFFFFFFFF00000000ULL) >> 32),
+		       (unsigned int)(dmamask & 0x00000000FFFFFFFFULL));
 		return -EOPNOTSUPP;
-#endif
 	}
 
 	err = -ENOMEM;