greybus: camera: fix data types of operations

In some operations definitions it was introduce some new fields with
the wrong data types, u8, instead of __u8. And because of this gbsim
build was broken.

Fixes: 3a1d7aa15bf6 ("greybus: Add camera protocol definition")

Signed-off-by: Rui Miguel Silva <rui.silva@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>