drivers/char/ppdev.c: 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>
Cc: Michael Buesch <mb@bu3sch.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/char/ppdev.c

@@ -287,12 +287,10 @@ static int register_device (int minor, struct pp_struct *pp)
 	char *name;
 	int fl;
 
-	name = kmalloc (strlen (CHRDEV) + 3, GFP_KERNEL);
+	name = kasprintf(GFP_KERNEL, CHRDEV "%x", minor);
 	if (name == NULL)
 		return -ENOMEM;
 
-	sprintf (name, CHRDEV "%x", minor);
-
 	port = parport_find_number (minor);
 	if (!port) {
 		printk (KERN_WARNING "%s: no associated port!\n", name);