Internal SDO requests now synchronized with external requests.
Internal SDO requests are managed by master FSM and can conflict with
external requests managed by slave FSM. The internal SDO requests
includes SDO requests created by an application and external request are
typical created by EtherCAT Tool for SDO upload/download or a directory
fetch initiated with ethercat sdos command. The conflict will cause a
FPWR from an external request to be overwritten by a FPWR from an
internal SDO request (or oppersite) in the same "train" of datagrams.

Maximum length of foe filename extended to 255.

Defined list_next_entry for older kernels.