drm/i915/guc: Use FAST_REQUEST for non-blocking H2G calls

In addition to the already defined REQUEST HXG message format,
which is used when sender expects some confirmation or data,
HXG protocol includes definition of the FAST REQUEST message,
that may be used when sender does not expect any useful data
to be returned.

Using this instead of GUC_HXG_TYPE_EVENT for non-blocking CTB requests
will allow GuC to send back GUC_HXG_TYPE_RESPONSE_FAILURE in case of
errors.

Note that it is not possible to return such errors to the caller,
since this is for non-blocking calls and the related fence is not
stored. Instead such messages are treated as unexpected, which will
give an indication of potential GuC misprogramming that warrants extra
debugging effort.

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Reviewed-by: John Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230526235538.2230780-2-John.C.Harrison@Intel.com