It seems to me as if there is something wrong in how the Cardbus version of epic100.c gets compiled when rebuilding 2.2.16-3. Line 1351 of drivers/net/epic100.c (which is part of a block wrapped by "#ifdef MODULE") calls epic100_probe. epic100_probe is defined at line 100, but it's wrapped by "#if !defined(CARDBUS) && !defined(HAS_PCI_NETIF)". So, when building epic_cb.o as a module, it can't call epic100_probe (hence an unresolved symbol).
epic100_probe is defined at line 300, not 100.
epic_cb not used anymore.