bpf: Fix cast to pointer from integer of different size warning

bpf: Fix cast to pointer from integer of different size warning

commit 2dedd7d2165565bafa89718eaadfc5d1a7865f66 upstream.

Fix "warning: cast to pointer from integer of different size" when
casting u64 addr to void *.

Fixes: a23740ec43ba ("bpf: Track contents of read-only maps as scalars")
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20191011172053.2980619-1-andriin@fb.com
Cc: Rafael David Tinoco <rafaeldtinoco@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>