msm: kgsl: Make sure that IB addresses are dword aligned

All IB GPU addresses should be dword aligned. Enforce that in software
to keep invalid addresses from bothering the CP.

Change-Id: Ic0dedbad2298ebbd20ca1b575b8e36dcbf5a1fbe
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>