drm/nouveau/gr/gf100: don't misuse kernel-doc comments

Change kernel-doc "/**" comments to common "/*" comments to prevent
kernel-doc warnings:

gf100.c:1044: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst
 * Wait until GR goes idle. GR is considered idle if it is disabled by the
gf100.c:1044: warning: missing initial short description on line:
 * Wait until GR goes idle. GR is considered idle if it is disabled by the
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Karol Herbst <kherbst@redhat.com>
Cc: Lyude Paul <lyude@redhat.com>
Cc: Danilo Krummrich <dakr@redhat.com>
Cc: nouveau@lists.freedesktop.org
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Danilo Krummrich <dakr@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231231233633.6596-3-rdunlap@infradead.org

drivers/gpu/drm/nouveau/nvkm/engine/gr/gf100.c

@@ -1040,7 +1040,7 @@ gf100_gr_zbc_init(struct gf100_gr *gr)
 	}
 }
 
-/**
+/*
  * Wait until GR goes idle. GR is considered idle if it is disabled by the
  * MC (0x200) register, or GR is not busy and a context switch is not in
  * progress.