For auto-dev, we'd probe the device node and get the axis ranges. If we
specify the device however we didn't retrieve the axis ranges and thus got
stuck with the defaults - losing out on automatic edge and accel calculation.

This is an issue if the device is hotplugged, as HAL will specify the device
node.

This patch adds another hook to synproto_operations to pre-probe the device.
This hook is only used by eventcomm and opens the FD, queries the axis range
and closes the FD again.