Preparatory work to use common host command code between ARM and x86.
Every command sends back explicitly the size of the response payload.
The size of the response defaults to 0 ond can be updated.
Add a protocol version number returned as command 0x00 to help with
backward compatibility.
move a couple of function from lpc specific header to host commands to
be able to implement them for the I2C link.
Signed-off-by: Vincent Palatin <vpalatin@chromium.org>
BUG=chrome-os-partner:9614
TEST=make BOARD=link
Change-Id: I6a28edf02996ddf6b7f32a3831d07d5f0271848f