ceph: get file size from fscrypt_file when present in inode traces

ceph: get file size from fscrypt_file when present in inode traces

When we get an inode trace from the MDS, grab the fscrypt_file field if
the inode is encrypted, and use it to populate the i_size field instead
of the regular inode size field.

Reviewed-by: Xiubo Li <xiubli@redhat.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>