ext2: Match up ext2_put_page() with ext2_dotdot() and ext2_find_entry()

ext2_dotdot() and ext2_find_entry() both require ext2_put_page() to be
called after successful return.  For some of the calls this
corresponding put was hidden in ext2_set_link and ext2_delete_entry().

Match up ext2_put_page() with ext2_dotdot() and ext2_find_entry() in the
functions which call them.  This makes the code easier to follow
regarding the get/put of the page.

Clean up comments to match new behavior.

To: Jan Kara <jack@suse.com>
Link: https://lore.kernel.org/r/20210329065402.3297092-2-ira.weiny@intel.com


Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Jan Kara <jack@suse.cz>