Commit "generic: ar8216: add mib_poll_interval switch attribute" has
added mib_poll_interval global config option and commit "generic:
ar8216: group MIB counters and use two basic ones only by default" has
added mib_type config option.
So this patch adds ucidef_set_ar8xxx_switch_mib helper function which
would allow configuration of the above mentioned new switch config
options.
Signed-off-by: Petr Štetiar <ynezz@true.cz>