HID: multitouch: Set to high latency mode on suspend.

Per Windows Precision Touchpad guidelines:

> The latency mode feature report is sent by the host to a Windows
> Precision Touchpad to indicate when high latency is desirable for
> power savings and, conversely, when normal latency is desired for
> operation.
>
> For USB-connected Windows Precision Touchpads, this enables the device
> to disambiguate between being suspended for inactivity (runtime IDLE)
> and being suspended because the system is entering S3 or Connected
> Standby.

The current implementation would set the latency to normal on device initialization,
but we didn't set the device to high latency on suspend.

Signed-off-by: Blaž Hrastnik <blaz@mxxn.io>
Acked-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>