driver core: Move driver_data back to struct device

Having to allocate memory as part of dev_set_drvdata() is a problem
because that memory may never get freed if the device itself is not
created. So move driver_data back to struct device.

This is a partial revert of commit b4028437.

Signed-off-by: Jean Delvare <jdelvare@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --cc drivers/base/base.h
Simple merge

diff --cc drivers/base/dd.c
Simple merge

diff --cc include/linux/device.h
Simple merge