gpu: introduce information dataspace

The current info implementation (as RPC) is limited in a few ways:

  * The amount of data that may be transferred is constrained by the
    underlying base platform
  * Most information never changes during run time but is copied
    nonetheless
  * The information differs depending on the used GPU device and
    in its current implementation only contains Intel GPU specific
    details

With this commit the 'info' RPC call is replaced with the
'info_dataspace' call that transfers the capability for the dataspace
containing the information only. This is complemented by a client
local 'attached_info' call that allows for getting typed access to
the information. The layout of the information is moved to its own
and GPU-specific header file, e.g., 'gpu/info_intel.h'

Issue #4265.

repos/os/include/gpu_session/client.h

@@ -37,8 +37,8 @@ class Gpu::Session_client : public Genode::Rpc_client<Session>
 		 ** Session interface **
 		 ***********************/
 
-		Info info() const override {
-			return call<Rpc_info>(); }
+		Genode::Dataspace_capability info_dataspace() const override {
+			return call<Rpc_info_dataspace>(); }
 
 		Gpu::Sequence_number exec_buffer(Buffer_id id,
 		                                 Genode::size_t size) override {