Driver core: Don't leak 'old_class_name' in drivers/base/core.c::device_rename()

If kmalloc() fails to allocate space for 'old_symlink_name' in
drivers/base/core.c::device_rename(), then we'll leak 'old_class_name'.

Spotted by the Coverity checker.


Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>