drm/tests/drm_kunit_helpers: Place correct function name in the comment header

Fixes the following W=1 kernel build warning(s):

 drivers/gpu/drm/tests/drm_kunit_helpers.c:172: warning: expecting prototype for drm_kunit_helper_context_alloc(). Prototype was for drm_kunit_helper_acquire_ctx_alloc() instead
Signed-off-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/20230824073710.2677348-10-lee@kernel.org
Link: https://lore.kernel.org/r/20230824073710.2677348-14-lee@kernel.org
[mripard: Squashed the two patches together]
Signed-off-by: Maxime Ripard <mripard@kernel.org>

drivers/gpu/drm/tests/drm_kunit_helpers.c

@@ -156,7 +156,7 @@ static void action_drm_release_context(void *ptr)
 }
 
 /**
- * drm_kunit_helper_context_alloc - Allocates an acquire context
+ * drm_kunit_helper_acquire_ctx_alloc - Allocates an acquire context
  * @test: The test context object
  *
  * Allocates and initializes a modeset acquire context.