powerpc/cell: Use vzalloc rather than vmalloc and memset in spu_alloc_lscsa_std

Hi,

We can get rid of a memset in
arch/powerpc/platforms/cell/spufs/lscsa_alloc.c::spu_alloc_lscsa_std() by
using vzalloc() rather than vmalloc()+memset().

Completely untested patch below since I have no hardware nor tools to
compile this.
Signed-off-by: Jesper Juhl <jj@chaosbits.net>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/platforms/cell/spufs/lscsa_alloc.c

@@ -36,10 +36,9 @@ static int spu_alloc_lscsa_std(struct spu_state *csa)
 	struct spu_lscsa *lscsa;
 	unsigned char *p;
 
-	lscsa = vmalloc(sizeof(struct spu_lscsa));
+	lscsa = vzalloc(sizeof(struct spu_lscsa));
 	if (!lscsa)
 		return -ENOMEM;
-	memset(lscsa, 0, sizeof(struct spu_lscsa));
 	csa->lscsa = lscsa;
 
 	/* Set LS pages reserved to allow for user-space mapping. */