apple_bce: fix C_CONNECT_STATUS during port reset

Only set the port change bit when the corresponding status bit
actually transitioned, instead of unconditionally flagging
C_CONNECT_STATUS on every port change event. Also clear any
flaky C_CONNECT_STATUS that the port change taskqueue may have
set while the bus lock was dropped during a successful port reset.

Reviewed by: adrian
Differential Revision: https://reviews.freebsd.org/D58875