x86: Fix uv bau sending buffer initialization

The initialization of the UV Broadcast Assist Unit's sending
buffers was making an invalid assumption about the
initialization of an MMR that defines its address.

The BIOS will not be providing that MMR.  So
uv_activation_descriptor_init() should unconditionally set it.

Tested on UV simulator.
Signed-off-by: NCliff Wickman <cpw@sgi.com>
Cc: <stable@kernel.org> # for v2.6.30.x
LKML-Reference: <E1MJTfj-0005i1-W8@eag09.americas.sgi.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

arch/x86/kernel/tlb_uv.c

@@ -711,7 +711,6 @@ uv_activation_descriptor_init(int node, int pnode)
 	unsigned long pa;
 	unsigned long m;
 	unsigned long n;
-	unsigned long mmr_image;
 	struct bau_desc *adp;
 	struct bau_desc *ad2;
 
@@ -727,12 +726,8 @@ uv_activation_descriptor_init(int node, int pnode)
 	n = pa >> uv_nshift;
 	m = pa & uv_mmask;
 
-	mmr_image = uv_read_global_mmr64(pnode, UVH_LB_BAU_SB_DESCRIPTOR_BASE);
-	if (mmr_image) {
-		uv_write_global_mmr64(pnode, (unsigned long)
-				      UVH_LB_BAU_SB_DESCRIPTOR_BASE,
-				      (n << UV_DESC_BASE_PNODE_SHIFT | m));
-	}
+	uv_write_global_mmr64(pnode, UVH_LB_BAU_SB_DESCRIPTOR_BASE,
+			      (n << UV_DESC_BASE_PNODE_SHIFT | m));
 
 	/*
 	 * initializing all 8 (UV_ITEMS_PER_DESCRIPTOR) descriptors for each