backlight: give platform_lcd the same name as the platform device.

When registering an platform_lcd, use the name of the platform device
specified in case there are more than one platform_lcd backlights
registered.

Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Cc: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>