greybus: arche-platform: make apb_state common to both platform drivers

Make 'enum apb_state' common to both platform drivers, so that
both drivers can make use of same state and user will have
unified control configuration across devices (SVC, APB1 and APB2)

Testing Done: Tested on EVT1.2 and DB3.5 platform.

Signed-off-by: Vaibhav Hiremath <vaibhav.hiremath@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>