CHROMIUM: WAR: misc: fastrpc: remove unused definition

BUG=b:137202421
TEST=Run label_image in loop

Signed-off-by: Jorge Ramirez-Ortiz <jorge.ramirez-ortiz@linaro.org>
Signed-off-by: Abhinav Asati <asatiabhi@codeaurora.org>
(cherry picked from commit 7b12b5d0c702420658b62bdf76786bd9c517662d
https://github.com/ldts/qualcomm-lt-kernel/commits/chromiumos-4.14-iommu-mmap-gw-rebased-for-next

)
Change-Id: Ica28e7d7774dc5fb688e7359df99ce75796dd3ac
Signed-off-by: Vamsi Singamsetty <vamssi@codeaurora.org>