fb: fix atyfb unused data warnings

Fix compiler warnings of data defined but not used by using the
__maybe_unused attribute.  The date are only used with certain kconfig
settings.

drivers/video/aty/atyfb_base.c:534:13: warning: 'ram_dram' defined but not used [-Wunused-variable]
drivers/video/aty/atyfb_base.c:535:13: warning: 'ram_resv' defined but not used [-Wunused-variable]

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc:	Paul Mackerras <paulus@samba.org>
Cc:	Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc:	linux-fbdev@vger.kernel.org
Cc:	Jean-Christophe Plagniol-Villard <plagnioj@jcrosoft.com>
Cc:	Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

drivers/video/aty/atyfb_base.c

@@ -58,6 +58,7 @@
 #include <linux/slab.h>
 #include <linux/vmalloc.h>
 #include <linux/delay.h>
+#include <linux/compiler.h>
 #include <linux/console.h>
 #include <linux/fb.h>
 #include <linux/init.h>
@@ -531,8 +532,8 @@ static int correct_chipset(struct atyfb_par *par)
 	return 0;
 }
 
-static char ram_dram[] = "DRAM";
-static char ram_resv[] = "RESV";
+static char ram_dram[] __maybe_unused = "DRAM";
+static char ram_resv[] __maybe_unused = "RESV";
 #ifdef CONFIG_FB_ATY_GX
 static char ram_vram[] = "VRAM";
 #endif /* CONFIG_FB_ATY_GX */