input: add new input event code to pass timestamp to userspace

There's timestamp jitter between the input events and input_sync.
Add two more event code to pass the timestamp to userspace. This
is needed since some input devices such as sensors need to retrieve
the accurate timestamp of the events generated.

Change-Id: I8d83739dfa4a70ca3877363c920bd5e3301f5494
Signed-off-by: Oliver Wang <mengmeng@codeaurora.org>