Revert self.ptc & self.delpc usage in dyn_core or decide to remove them

[FlorianDeconinck]

A memory leak was introduced by VRAM pooling due to the particular pattern in using self.ptc and self.delpc as return value read of C_SW. Those where remove in PR #319 to plug the leak.
A soon-to-be released version of DaCe deals with it at the source and once merged we could remove the workaround, which to use the internal C_SW ptc and delpc.
Another option to do away with the dyn_core allocated ones, since this only adds a copy