msm: kgsl: Maintain a list of global pagetable entries

Store "global" pagetable entries in a master list and use
that list to automatically set and add the entries to
pagetables as they are created.

Change-Id: Ic0dedbad1b216539c8e3b7290f415e410be51792
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>
Signed-off-by: Shubhraprakash Das <sadas@codeaurora.org>