ext4: fix memory leak in ext4_ext_shift_extents()

ext4: fix memory leak in ext4_ext_shift_extents()

In ext4_ext_shift_extents(), if the extent is NULL in the while loop, the
function returns immediately without releasing the path obtained via
ext4_find_extent(), leading to a memory leak.

Fix this by jumping to the out label to ensure the path is properly
released.

Fixes: a18ed359bdddc ("ext4: always check ext4_ext_find_extent result")
Signed-off-by: Zilin Guan <zilin@seu.edu.cn>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Baokun Li <libaokun1@huawei.com>
Link: https://patch.msgid.link/20251225084800.905701-1-zilin@seu.edu.cn
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org