mtd: block2mtd: Use kasprintf

kasprintf combines kmalloc and sprintf, and takes care of the size
calculation itself.

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

// <smpl>
@@
expression a,flag;
expression list args;
statement S;
@@

  a =
-  \(kmalloc\|kzalloc\)(...,flag)
+  kasprintf(flag,args)
  <... when != a
  if (a == NULL || ...) S
  ...>
- sprintf(a,args);
// </smpl>
Signed-off-by: NJulia Lawall <julia@diku.dk>
Signed-off-by: NDavid Woodhouse <David.Woodhouse@intel.com>

drivers/mtd/devices/block2mtd.c

@@ -275,12 +275,10 @@ static struct block2mtd_dev *add_device(char *devname, int erase_size)
 
 	/* Setup the MTD structure */
 	/* make the name contain the block device in */
-	name = kmalloc(sizeof("block2mtd: ") + strlen(devname) + 1,
-			GFP_KERNEL);
+	name = kasprintf(GFP_KERNEL, "block2mtd: %s", devname);
 	if (!name)
 		goto devinit_err;
 
-	sprintf(name, "block2mtd: %s", devname);
 	dev->mtd.name = name;
 
 	dev->mtd.size = dev->blkdev->bd_inode->i_size & PAGE_MASK;