msm: kgsl: Re-export the UAPI header

Commit 7a6368ee ("msm: kgsl: Add support for the Adreno GPU") stopped
exporting the uapi header. Unfortunately not all the user-mode libraries
got the message. Start exporting it again to prevent breakage while
everybody figures out how to transition correctly.

Change-Id: Ic0dedbadc187d018b9ff34c0a93f156d525e8b16
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>