fs/char_dev.c: remove useless loop

There are two useless lines in fs/char_dev.c.

In register_chrdev there is a loop to change all '/' into '!' in the
kernel object name.
This code is useless as the same substitution is in kobject_set_name_vargs in
lib/kobject.c:
228         /* ewww... some of these buggers have '/' in the name ... */
229         while ((s = strchr(kobj->name, '/')))
230                 s[0] = '!';

kobject_set_name_vargs is called by kobject_set_name.
kobject_set_name is called just above the useless loop.

[hidave.darkstar@gmail.com: fix warning, remove the unused char *s]
Signed-off-by: Renzo Davoli <renzo@cs.unibo.it>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Dave Young <hidave.darkstar@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>