Use abstract nvgpu_rwsem as TSG channel list lock instead of the Linux specific rw_semaphore. JIRA NVGPU-259 Change-Id: I41a38b29d4651838b1962d69f102af1384e12cb6 Signed-off-by: Terje Bergstrom <tbergstrom@nvidia.com> Reviewed-on: https://git-master.nvidia.com/r/1579935 Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com> Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>