fbdev/atyfb: Fix 2 defined-but-not-used warnings

If CONFIG_FB_ATY_BACKLIGHT=y but CONFIG_PCI=n:

drivers/video/aty/atyfb_base.c:2272: warning: ‘aty_bl_exit’ defined but not used

If CONFIG_ATARI=y for a modular build:

drivers/video/aty/atyfb_base.c:2794: warning: ‘store_video_par’ defined but not
used

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>