Input: sentelic - refactor code for upcoming new hardware support

- Move event bits setup code into a separate function,
  fsp_set_input_params(), so that we can perform hardware-specific settings
  in the future;
- Take hardware version information into account when activating
  protocol;
- Remove button information from boot message as it's somewhat confusing
  and is only for internal processing. While there, also move button
  retrieval code to be a part of protocol activation process.

Signed-off-by: Tai-hwa Liang <avatar@sentelic.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>