pid: add missing override specifiers
pid: add missing override specifiers

[pid/controller.hpp:18] -> [pid/pidcontroller.hpp:28]: (style) The
function 'inputProc' overrides a function in a base class but is not
marked with a 'override' specifier.
[pid/controller.hpp:20] -> [pid/pidcontroller.hpp:30]: (style) The
function 'outputProc' overrides a function in a base class but is not
marked with a 'override' specifier.
[pid/controller.hpp:22] -> [pid/pidcontroller.hpp:32]: (style) The
function 'process' overrides a function in a base class but is not
marked with a 'override' specifier.
[pid/controller.hpp:24] -> [pid/pidcontroller.hpp:34]: (style) The
function 'getID' overrides a function in a base class but is not marked
with a 'override' specifier.

Change-Id: I29a6bbe644a5f7aad933eb49e7b6f7fdc6e33f19
Signed-off-by: Patrick Venture <36c53fa43f47f3fd67cb2fc38031827244d18a1f@google.com>

openbmc/phosphor-pid-control,openbmc/phosphor-pid-control