Move channel IOCTL specific code to Linux module. This clears some Linux dependencies from channel_gk20a.c. JIRA NVGPU-32 Change-Id: I41817d612b959709365bcabff9c8a15f2bfe4c60 Signed-off-by: Terje Bergstrom <tbergstrom@nvidia.com> Reviewed-on: http://git-master/r/1330804 Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com> Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>