Fix stacking of rx receive functions

Fix stacking of rx receive functions

PROX can stack different RX functions, so that they are executed
after each other.
This feature is for instance used to dump packets or to print
distribution of receive packets, without influencing the performance
of the rx functions when no dump or print is needed.
The previous implementation was wrong and causing some of the stacked
functions not to be executed. This was causing for instance issues
in latency measurement after enabling dumping packets.

Change-Id: I766b8ee8e8852fa17cdaf60ee6e1fec0dc98c719
Signed-off-by: Xavier Simonart <xavier.simonart@intel.com>