The init/exit hooks in platform data are being used nowhere, so can
be removed.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Cc: Darius Augulis <augulis.darius@gmail.com>
Cc: Ben Dooks <ben-linux@fluff.org>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>