ext4: Move marking of handle as sync to ext4_add_nondir()

Every caller of ext4_add_nondir() marks handle as sync if directory has
DIRSYNC set. Move this marking to ext4_add_nondir() so reduce some
duplication.

Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20191105164437.32602-4-jack@suse.cz


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