x86, uv, uv3: Check current gru hub support for SGI UV3

This patch checks current hub support to avoid panicing the
system until all the GRU changes for UV3+ are in place.

Signed-off-by: Mike Travis <travis@sgi.com>
Link: http://lkml.kernel.org/r/20130211194509.035828372@gulag1.americas.sgi.com
Acked-by: Dimitri Sivanich <sivanich@sgi.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

drivers/misc/sgi-gru/grufile.c

@@ -517,7 +517,7 @@ static int __init gru_init(void)
 {
 	int ret;
 
-	if (!is_uv_system())
+	if (!is_uv_system() || (is_uvx_hub() && !is_uv2_hub()))
 		return 0;
 
 #if defined CONFIG_IA64