Add an api for early initialization of input udev

Add an api for early initialization of input udev

KERNEL[3.864698] add      /devices/virtual/rc/rc1/input2 (input)
DEVPATH=/devices/virtual/rc/rc1/input2
UDEV  [6.541278] add      /devices/virtual/rc/rc1/input2 (input)
DEVPATH=/devices/virtual/rc/rc1/input2

For fast input accessing, input udev should be set up early,
so that udev_device_get_is_initialized(input_udev_dev) check can be skipped before UDEV [6.541278].

Change-Id: I8182f856b0169f9c434bb360a49cfef109485c94
Signed-off-by: Hyotaek Shim <hyotaek.shim@samsung.com>