drivers/video/aty/aty128fb.c: fix a warning pertaining to the aty128fb backlight variable

Fix the following warning in the aty128fb driver:

drivers/video/aty/aty128fb.c:363:12: warning: 'backlight' defined but not used [-Wunused-variable]
static int backlight = 0;
^

as the variable's value is only read if CONFIG_FB_ATY128_BACKLIGHT=y. The
variable is also set if MODULE is unset[*].

[*] I wonder if the conditional wrapper around aty128fb_setup() should be
using CONFIG_MODULE rather than MODULE.

Signed-off-by: David Howells <[e-mail]>
Cc: Paul Mackerras <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/video/aty/aty128fb.c

···
 static bool mtrr = true;
 #endif
 
+#ifdef CONFIG_FB_ATY128_BACKLIGHT
 #ifdef CONFIG_PMAC_BACKLIGHT
 static int backlight = 1;
 #else
 static int backlight = 0;
+#endif
 #endif
 
 /* PLL constants */
···
 			default_crt_on = simple_strtoul(this_opt+4, NULL, 0);
 			continue;
 		} else if (!strncmp(this_opt, "backlight:", 10)) {
+#ifdef CONFIG_FB_ATY128_BACKLIGHT
 			backlight = simple_strtoul(this_opt+10, NULL, 0);
+#endif
 			continue;
 		}
 #ifdef CONFIG_MTRR