eventfd is pointer. As such, it should be initialized to NULL, not to 0.

In addition, no need to initialize it after creation because the
entire structure is zeroed-out. Also, no need to initialize it before
release because the entire structure is freed.
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Oded Gabbay <ogabbay@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>