ext4: lost matching-pair of trace in ext4_truncate

It should call trace exit in all return path for ext4_truncate.

Signed-off-by: zhengliang <zhengliang6@huawei.com>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Reviewed-by: Ritesh Harjani <riteshh@linux.ibm.com>
Link: https://lore.kernel.org/r/20200701083027.45996-1-zhengliang6@huawei.com


Signed-off-by: Theodore Ts'o <tytso@mit.edu>