drm/nouveau: remove unused tu102_gr_load() function

tu102_gr_load() is completely unused and can be removed to address
this warning:

drivers/gpu/drm/nouveau/dispnv50/disp.c:2517:1: error: no previous prototype for 'nv50_display_create'

Another patch was sent in the meantime to mark the function static but
that would just cause a different warning about an unused function.

Fixes: 1cd97b54

 ("drm/nouveau/gr/tu102-: use sw_veid_bundle_init from firmware")
Link: https://lore.kernel.org/all/CACO55tuaNOYphHyB9+ygi9AnXVuF49etsW7x2X5K5iEtFNAAyw@mail.gmail.com/
Link: https://lore.kernel.org/all/20230417210310.2443152-1-arnd@kernel.org/
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Karol Herbst <kherbst@redhat.com>
Signed-off-by: Karol Herbst <kherbst@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230803143358.13563-1-arnd@kernel.org