i2c-cht-wc: Workaround CHT GPIO controller IRQ issues

i2c-cht-wc: Workaround CHT GPIO controller IRQ issues

The Cherry Trail Whiskey Cove PMIC's IRQ line is attached to one of
the GPIOs of the Cherry Trail SoC. The CHT GPIO controller sometimes
fails to deliver IRQs (seen when there is an IRQ storm on another pin).

This commit works around this by reducing the long timeout which was
a poor attempt to workaround this from 3s to 30ms and after that
manually checking the status register for transfer completion by
calling the threaded IRQ handler directly.

This is safe todo as the entire threaded IRQ handler is protected
by a mutex.

Note 30ms should be more then long enough, at 100KHz any smbus single
byte transaction should be finished in 4ms.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>