sfc: Use CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS where appropriate

For some buffers we use a starting offset of either NET_IP_ALIGN or 0
depending on whether we believe the architecture supports efficient
access to unaligned words.  There is now a config macro specifying
whether this is the case, so check that rather than checking for
specific architectures.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
diff --git a/drivers/net/sfc/net_driver.h b/drivers/net/sfc/net_driver.h
index 868ad1e..cdb11fa 100644
--- a/drivers/net/sfc/net_driver.h
+++ b/drivers/net/sfc/net_driver.h
@@ -474,7 +474,7 @@
  * This is the equivalent of NET_IP_ALIGN [which controls the alignment
  * of the skb->head for hardware DMA].
  */
-#if defined(__i386__) || defined(__x86_64__)
+#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
 #define EFX_PAGE_IP_ALIGN 0
 #else
 #define EFX_PAGE_IP_ALIGN NET_IP_ALIGN