arcnet: com20020: Use arcnet_<I/O> routines

Simplify and make consistent the current uses of inb/outb
by using the newly introduced arcnet_<I/O> equivalents.

o Add new #defines for register offsets
  There is an register offset, 8, that is unnamed and used as-is.
o Remove old #defines that included the ioaddr
o Remove obfuscating macros by expanding them in-place where appropriate
o Create static inline com20020_set_subaddress for the SET_SUBADR macro

There is an unused arcnet config entry CONFIGSA100_CT6001 which added a
special #define BUS_ALIGN which was introduced but never used in fullhist git
tree commit 22cfce4b82b0 ("[ARCNET]: Fixes.") in Nov 2004 for Linux v2.6.10.

This BUS_ALIGN #define tries to allow 8 bit devices to work on a 16 bit
bus by aligning addresses to 16 bit boundaries.

Move this currently unused CONFIG_SA1100_CT6001 BUS_ALIGN macro from
com20020.h to arcdevice.h.

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Michael Grzeschik <m.grzeschik@pengutronix.de>