jbd2: fix clang warning in recovery.c

Remove unused variable store which was never used.

This fix is also in e2fsprogs commit 99a2294f85f0 ("e2fsck: value
stored to err is never read").

Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>