Move the gpgpu struct from cl_command_queue to thread specific context

Move the gpgpu struct from cl_command_queue to thread specific context

We find some cases will use multi-threads to run on the same queue,
executing the same kernel. This will cause the gpgpu struct which
is very important for GPU context setting be destroyed because we
do not implement any sync protect on it now.
Move the gpgpu struct into thread specific space will fix this problem
because the lib_drm will do the GPU command serialization for us.

Reviewed-by: Zhigang Gong <zhigang.gong@linux.intel.com>
Reviewed-by: "Zou, Nanhai" <nanhai.zou@intel.com>