Implements missing OMAPUnmapMem function body.
Implements missing OMAPUnmapMem function body.

(cherry picked from commit 34579dc86d0546aed6c145b5e9f1e611541d5b5e)
From linaro: git://git.linaro.org/arm/xorg/driver/xf86-video-armsoc.git

Signed-off-by: Daniel Kurtz <31914e832df1cd8e5daa417106c0c6f5297b27d7@chromium.org>

BUG=chromium:260197
TEST=manual build and sanity check on device

Change-Id: If2d93fdc758264b1f9646e50eae13751553f606d
Reviewed-on: https://chromium-review.googlesource.com/62167
Reviewed-by: Daniel Kurtz <31914e832df1cd8e5daa417106c0c6f5297b27d7@chromium.org>
Tested-by: Daniel Kurtz <31914e832df1cd8e5daa417106c0c6f5297b27d7@chromium.org>
Commit-Queue: Daniel Kurtz <31914e832df1cd8e5daa417106c0c6f5297b27d7@chromium.org>

markyzq/armsoc-rockchip,markyzq/armsoc-rockchip