A pointer to a probe callback is passed to the core via
platform_driver_register and so the function must not disappear when the
.init sections are discarded.  Otherwise (if also having HOTPLUG=y)
unbinding and binding a device to the driver via sysfs will result in an
oops as does a device being registered late.

An alternative to this patch is using platform_driver_probe instead of
platform_driver_register plus removing the pointer to the probe function
from the struct platform_driver.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ben Dooks <ben-linux@fluff.org>
Cc: Dmitry Baryshkov <dbaryshkov@gmail.com>
Cc: Eric Miao <eric.miao@marvell.com>
Cc: Liam Girdwood <liam.girdwood@wolfsonmicro.com>
Cc: Paul Sokolovsky <pmiscml@gmail.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
Cc: Russell King <rmk+kernel@arm.linux.org.uk>
Acked-by: Arnaud Patard <arnaud.patard@rtp-net.org>
Acked-by: Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>
Acked-by: Kristoffer Ericson <kristoffer.ericson@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>