xfs: fix uninitialized error variable

A previous commit removed the initialization of variable 'error' to zero,
and can cause a bogus error return.  This occurs when error contains a
non-zero garbage value and the call to xchk_should_terminate detects a
pending fatal signal and checks for a zero error before setting it
to -EAGAIN. Fix the issue by initializing error to zero.

Fixes: b9454fe0 ("xfs: clean up the inode cluster checking in the inobt scrub")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

fs/xfs/scrub/ialloc.c

@@ -161,7 +161,7 @@ xchk_iallocbt_check_cluster_ifree(
 	bool				irec_free;
 	bool				ino_inuse;
 	bool				freemask_ok;
-	int				error;
+	int				error = 0;
 
 	if (xchk_should_terminate(bs->sc, &error))
 		return error;