Check the return value of platform_device_register_simple().

Cc: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: NAkinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>