UPSTREAM: iio: cros_ec_sensors: Flush when changing the FIFO timeout

|hwfifo_timeout| is used by the EC firmware only when new samples are
available.
When the timeout changes, espcially when the new timeout is shorter than
the current one, send the samples waiting in the FIFO to the host.
Inline the call to transmit |hwfifo_timeout| value to the firmware.

Now flush when a sensor is suspended (ODR set to 0) as well.

Signed-off-by: Gwendal Grignou <gwendal@chromium.org>
Link: https://patch.msgid.link/20250423220506.2061021-1-gwendal@chromium.org


Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
(cherry picked from commit e50cf7e2)

Bug: 381480028
Bug: 356723377
Test: Check CTS on AL, tast hardware.SensorIioserviceHard

Change-Id: I5a3a3db7777958a26e1e48de48c6bded42b6ba27
Signed-off-by: Gwendal Grignou <gwendal@google.com>