block: drop double zeroing

sg_init_table zeroes its first argument, so the allocation of that argument
doesn't have to.

the semantic patch that makes this change is as follows:
(http://coccinelle.lip6.fr/)

// <smpl>
@@
expression x;
@@

x =
- kzalloc
+ kmalloc
 (...)
...
sg_init_table(x,...)
// </smpl>
Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/bsg-lib.c

@@ -207,7 +207,7 @@ static int bsg_map_buffer(struct bsg_buffer *buf, struct request *req)
 
 	BUG_ON(!req->nr_phys_segments);
 
-	buf->sg_list = kzalloc(sz, GFP_KERNEL);
+	buf->sg_list = kmalloc(sz, GFP_KERNEL);
 	if (!buf->sg_list)
 		return -ENOMEM;
 	sg_init_table(buf->sg_list, req->nr_phys_segments);