coresight: fix GenericMemAPTarget issues. (#1350)
coresight: fix GenericMemAPTarget issues. (#1350)

* coresight: revert superclass of GenericMemAPTarget to CoreSightCoreComponent.

This fixes an issue where DebugContext tries to access .core if the
parent is not a CoreSightCoreComponent.

* coresight: GenericMemAPTarget: raise CoreRegisterAccessError for core register methods.

* coresight: GenericMemAPTarget: pass .read_memory() 'now' arg to AP.
pyocd/pyOCD,flit/pyOCD,flit/pyOCD,pyocd/pyOCD