Add new unit common/gr/subctx.c to manage GR subcontext
This unit provides interfaces to allocate/free/load GR subcontext
Add new header file include/nvgpu/gr/subctx.h to declare all the
interfaces.
Right now channel_gk20a structure directly includes a nvgpu_mem
for context header.
Declare a new structure nvgpu_gr_subctx for subcontext and include
this from channel_gk20a
Make all necessary changes to refer ctx_header from subctx instead
of directly referencing it from channel
Jira NVGPU-1613
Change-Id: I9eb1ee8f26fa88d2881f9b294935b65e9cbcc9b4
Signed-off-by: Deepak Nibade <dnibade@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/1990129
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>
