yaffs: fix misplaced variable declaration

A variable declaration landed one function higher than intended,
leading to an unused variable warning for configurations with
YAFFS_USE_DIR_ITERATE=y and a build failure for configurations
with the same being unset.

Fixes: "yaffs: Fix build failure by handling inode i_version with proper atomic API"
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>