backlight/bd6107: Compare against struct fb_info.device

Struct bd6107_platform_data refers to a platform device within
the Linux device hierarchy. The test in bd6107_backlight_check_fb()
compares it against the fbdev device in struct fb_info.dev, which
is different. Fix the test by comparing to struct fb_info.device.

Fixes a bug in the backlight driver and prepares fbdev for making
struct fb_info.dev optional.

v2:
* move renames into separate patch (Javier, Sam, Michael)

Fixes: 67b43e590415 ("backlight: Add ROHM BD6107 backlight driver")
Signed-off-by: Thomas Zimmermann <[e-mail]>
Cc: Laurent Pinchart <[e-mail]>
Cc: Lee Jones <[e-mail]>
Cc: Daniel Thompson <[e-mail]>
Cc: Jingoo Han <[e-mail]>
Cc: [e-mail]
Cc: <[e-mail]> # v3.12+
Reviewed-by: Javier Martinez Canillas <[e-mail]>
Reviewed-by: Sam Ravnborg <[e-mail]>
Reviewed-by: Daniel Thompson <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/video/backlight/bd6107.c

···
 {
 	struct bd6107 *bd = bl_get_data(backlight);
 
-	return bd->pdata->fbdev == NULL || bd->pdata->fbdev == info->dev;
+	return bd->pdata->fbdev == NULL || bd->pdata->fbdev == info->device;
 }
 
 static const struct backlight_ops bd6107_backlight_ops = {