minui: Support input device hotplug in recovery mode.

In the old code, the recovery only enumerated the input devices at the
startup, and read the input events from these devices.
So if a USB input device is probed after the recovery startup, then the
recovery can't read the events from this device.
This patch use inotify to monitor /dev/input for new added input
device, then support input device hotplug in recovery mode.

Bug: 111847510
Test: can use USB keyboard hotplugged in recovery mode
Change-Id: I7e7dcbd619d3c66a2f40a43418f5dac6a50c859e
Signed-off-by: Liu Shuo A <shuo.a.liu@intel.com>
Signed-off-by: Ming Tan <ming.tan@intel.com>