fbdev: atyfb: add stubs for aty_{ld,st}_lcd()

Fix build errors when these functions are not defined.

../drivers/video/fbdev/aty/atyfb_base.c: In function 'aty_power_mgmt':
../drivers/video/fbdev/aty/atyfb_base.c:2002:7: error: implicit declaration of function 'aty_ld_lcd'; did you mean 'aty_ld_8'? [-Werror=implicit-function-declaration]
 2002 |  pm = aty_ld_lcd(POWER_MANAGEMENT, par);
../drivers/video/fbdev/aty/atyfb_base.c:2004:2: error: implicit declaration of function 'aty_st_lcd'; did you mean 'aty_st_8'? [-Werror=implicit-function-declaration]
 2004 |  aty_st_lcd(POWER_MANAGEMENT, pm, par);
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reported-by: kernel test robot <lkp@intel.com>
Cc: linux-fbdev@vger.kernel.org
Cc: dri-devel@lists.freedesktop.org
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: David Airlie <airlied@linux.ie>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210222032853.21483-1-rdunlap@infradead.org

drivers/video/fbdev/aty/atyfb_base.c

@@ -175,6 +175,15 @@ u32 aty_ld_lcd(int index, const struct atyfb_par *par)
 		return aty_ld_le32(LCD_DATA, par);
 	}
 }
+#else /* defined(CONFIG_PMAC_BACKLIGHT) || defined(CONFIG_FB_ATY_BACKLIGHT) \
+	 defined(CONFIG_FB_ATY_GENERIC_LCD) */
+void aty_st_lcd(int index, u32 val, const struct atyfb_par *par)
+{ }
+
+u32 aty_ld_lcd(int index, const struct atyfb_par *par)
+{
+	return 0;
+}
 #endif /* defined(CONFIG_PMAC_BACKLIGHT) || defined (CONFIG_FB_ATY_GENERIC_LCD) */
 
 #ifdef CONFIG_FB_ATY_GENERIC_LCD