[PATCH] vt: Honor the return value of device_create_file

Check the return value of device_create_file().  If return is 'fail', remove
attributes by calling device_remove_file().

Signed-off-by: Antonino Daplas <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>