Input: add wm97xx accelerated driver for Atmel microprocessors

This patch adds an accelerated driver for Atmel AVR32 AT32AP700X
microprocessors. It uses interrupts on the channel B in the AC97
controller. Thus, offloading the work queue in the wm97xx-ts driver.

The driver has been tested with Atmel AVR32 AT32AP7000 and Wolfson
WM9712 codec.

The driver can also be easily modified to support Atmel AT91 devices, as
AT91 and AVR32 share the same AC97C module.

[Fixed leak of atmel_wm97xx when probe fails. -- broonie]
[dtor@mail.ru: do not report ABS_PRESSURE events when not measuring pressure]
Signed-off-by: Hans-Christian Egtvedt <hans-christian.egtvedt@atmel.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>