The ad7879 driver is using the old bus method of only supporting one
at a time (I2C or SPI). So refactor it like the other input drivers
that support multiple busses simultaneously.
Signed-off-by: NMike Frysinger <vapier@gentoo.org>
Signed-off-by: NMichael Hennerich <michael.hennerich@analog.com>
Signed-off-by: NDmitry Torokhov <dtor@mail.ru>