Driver core: add device_create_vargs and device_create_drvdata

We want to have the drvdata field set properly when creating the device
as sysfs callbacks can assume it is present and it can race the later
setting of this field.

So, create two new functions, deviec_create_vargs() and
device_create_drvdata() that take this new field.

device_create_drvdata() will go away in 2.6.27 as the drvdata field will
just be moved to the device_create() call as it should be.

Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>