lib: Fix atomic64_inc_not_zero test

atomic64_inc_not_zero must return 1 if it perfomed the add and 0 otherwise.
The test assumed the opposite convention.

Signed-off-by: Luca Barbieri <luca@luca-barbieri.com>
LKML-Reference: <1267469749-11878-5-git-send-email-luca@luca-barbieri.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>