SiS warning fixes

Somehow the sis_info133 external definition ended up in libata.h and that
was included by both drivers.  However libata.h contains libata-* specific
internals and clashing defines like DRV_NAME so this makes a mess.  Move
the extern into the C file and remove the warnings

[akpm@linux-foundation.org: create sis.h to avoid extern-decl-in-C]
Signed-off-by: Alan Cox <alan@redhat.com>
Cc: Jeff Garzik <jeff@garzik.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

drivers/ata/pata_sis.c

@@ -32,9 +32,8 @@
 #include <scsi/scsi_host.h>
 #include <linux/libata.h>
 #include <linux/ata.h>
-#include "libata.h"
+#include "sis.h"
 
-#undef DRV_NAME		/* already defined in libata.h, for libata-core */
 #define DRV_NAME	"pata_sis"
 #define DRV_VERSION	"0.4.5"