base-files: Create /var/preferences

:Release Notes:
Create /var/preferences with mode 755 to protect the directory's files
from being removed or modified.

:Detailed Notes:

:Testing Performed:
Confirmed that /var/preferences was created with mode 755.

:QA Notes:

:Issues Addressed:
[GF-39768] Is it safe for /var/preferences to be world-writable?
[GF-52345] CCC: base-files=webos6

Open-webOS-DCO-1.0-Signed-off-by: Seonho Park <seonho.park@lge.com>
Change-Id: If3c598575288ec91685471f2dd29e5421901662e
Reviewed-on: https://g2g.palm.com/3903
Reviewed-by: DCO Verification
Reviewed-by: Seonho Park <seonho.park@lge.com>
Tested-by: Seonho Park <seonho.park@lge.com>
Reviewed-by: Susan Montooth <susan.montooth@lge.com>
Tested-by: Joungyong Choi <joungyong.choi@lge.com>
Reviewed-by: Joungyong Choi <joungyong.choi@lge.com>