Documentation: devres: add allocation functions to list of supported calls

Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Randy Dunlap <rdunlap@xenotime.net>
Cc: Greg KH <gregkh@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>