msm: Change devicetree prefix to qti for Ion and memory reserve

The preferred prefix for devicetree is now 'qti' instead of 'qcom'.
Change the prefix for devicetree bindings for memory reservations
and Ion.

Change-Id: Ic524eb4cfc9b9ab33a376606abc75eb244330123
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>