drm/nouveau/acr/ga102: set variable ga102_gsps storage-class-specifier to static

drm/nouveau/acr/ga102: set variable ga102_gsps storage-class-specifier to static

smatch reports
drivers/gpu/drm/nouveau/nvkm/subdev/gsp/ga102.c:49:1: warning: symbol
  'ga102_gsps' was not declared. Should it be static?

This variable is only used in its defining file, so it should be static

Signed-off-by: Tom Rix <trix@redhat.com>
Reviewed-by: Karol Herbst <kherbst@redhat.com>
Signed-off-by: Karol Herbst <kherbst@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230517133112.873856-1-trix@redhat.com