Driver core: coding style cleanup

This converts code of the form

	if ((error = some_func()))
		goto fixup;
to
	error = some_func();
	if (error)
		goto fixup;

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>