greybus: Remove bridge PHY protocol specific classes

These protocols are managed under the bridged PHY class and doesn't need
protocol specific classes anymore.

Remove their entries from gb_gpbridge_id_table array and remove the now
unused macro's and mark their values as unused.

Tested on EVT 1.5 with generic-test module.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Sandeep Patil <sspatil@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>