staging: comedi: drivers (core): factor out async subdevice postconfig
Factor the setup of an async subdevice out of postconfig(). This allows
bringing the code back a couple indents and makes the postconfig a bit
clearer.
For aesthetic reasons, rename postconfig() to __comedi_device_postconfig().
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com> Cc: Ian Abbott <abbotti@mev.co.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>