drm/i915/selftests: Use less in contexts steal guc id test

Using more guc_ids in the stealing guc id test has no real benefit.
Tearing down lots of contexts all at the same time takes a bit of time
due to the H2G / G2H ping-pong with the GuC. On some slower platforms
this can cause timeous when flushing the test as the GT isn't idle when
this ping-pong is happening. Reduce the number of guc ids to speed up
the flushing of the test.

Link: https://gitlab.freedesktop.org/drm/intel/-/issues/4821Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220122000822.25616-1-matthew.brost@intel.com

drivers/gpu/drm/i915/gt/uc/selftest_guc.c

@@ -157,7 +157,7 @@ static int intel_guc_steal_guc_ids(void *arg)
 	wakeref = intel_runtime_pm_get(gt->uncore->rpm);
 	engine = intel_selftest_find_any_engine(gt);
 	sv = guc->submission_state.num_guc_ids;
-	guc->submission_state.num_guc_ids = 4096;
+	guc->submission_state.num_guc_ids = 512;
 
 	/* Create spinner to block requests in below loop */
 	ce[context_index] = intel_context_create(engine);