base-files: Create /media/internal to be writeable by all

:Release Notes:
webOS expects /media/internal (${webos_mountablestoragedir}) to be
writeable by all (because it's typically been mounted on a VFAT
partition, which doesn't enforce permissions).

:Detailed Notes:
Also, remove the extraneous parent directory of ${webos_db8datadir}/temp
from dirs700 (install -d creates parent directories).

:Testing Performed:
Confirmed that image contains this directory with the expected
permissions.

:QA Notes:

:Issues Addressed:
[GF-34330] /media/internal (webos_mountablestoragedir) must be writeable
           by all
[GF-35143] CCC: base-files=webos2

Open-webOS-DCO-1.0-Signed-off-by: Herb Kuta <herb.kuta@lge.com>
Change-Id: I3a2d7ef2823eb48c4e717aa0ad7b11a70f5fea4e
Reviewed-on: https://g2g.palm.com/3272
Tested-by: Herb Kuta <herb.kuta@lge.com>
Reviewed-by: Susan Montooth <susan.montooth@lge.com>