This patch moves the ASIX AX8817x driver into its own file, just using
the "usbnet" infrastructure as a utility library.

 - As with "cdc_subset" this involved minor Kconfig/kbuild tweaks,
   moving code from one file to another, and exporting a few functions.

 - This includes updates from Jamie Painter to add (and use) a new hook
   to handle the different maximum transfer sizes for rx and tx sides.

 - Also from Jamie, some bugfixes:
    * MDIO byteorder (to address some PPC media negotiation problems);
    * Force alignment at key spots when using ax88772 framing (on some
      embedded hardware, the network stack will break otherwise);
    * Address some link reset problems.

It also makes this driver use the standard (5 seconds vs half second)
control timeouts used elsewhere in USB; and wraps a few lines before
the 80th column (which previously needed it).
Signed-off-by: NDavid Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>