Fix pkg_upgrade tool

Fix pkg_upgrade tool

- Change filter to get preload pkg to retrieve readonlyupdate pkgs.
- When pkg is readonlyupdated but not included at image,
  set its db attribute properly to treat as normal pkg.(TODO)
- When pkg is readnolyupdated and update image has same version,
  readonlyupdate should be uninstalled except its rwdata.

Related changes:
[pkgmgr-info] : https://review.tizen.org/gerrit/#/c/170323/

Change-Id: I9ae7f5567034a5c44c0eb8cd62a0b138e6626d27
Signed-off-by: Junghyun Yeon <jungh.yeon@samsung.com>