hwmon: lis3: Enhance lis3 selftest with IRQ line test

Configure chip to data ready mode in selftest and count received
interrupts to see that interrupt line(s) are working.

Signed-off-by: Samu Onkalo <samu.p.onkalo@nokia.com>
Acked-by: Eric Piel <eric.piel@tremplin-utc.net>
Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>