backlight: Separate backlight properties from backlight ops pointers

Per device data such as brightness belongs to the indivdual device
and should therefore be separate from the the backlight operation
function pointers. This patch splits the two types of data and
allows simplifcation of some code.

Signed-off-by: Richard Purdie <rpurdie@rpsys.net>

arch/powerpc/kernel/traps.c

@@ -107,7 +107,7 @@ int die(const char *str, struct pt_regs *regs, long err)
 	if (machine_is(powermac) && pmac_backlight) {
 		struct backlight_properties *props;
 
-		props = pmac_backlight->props;
+		props = &pmac_backlight->props;
 		props->brightness = props->max_brightness;
 		props->power = FB_BLANK_UNBLANK;
 		backlight_update_status(pmac_backlight);