While comparing arch/ppc/8xx_io/enet.c with the version in kernel 2.4.36.2 I saw that PC_ENET_LBK is not defined in any of the 2.6.25.4 header files.
maybe it`s related to this commit: http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=8b1a97776d0e4ad76e1e350e7ec1f4406af5f9e1 did you just notice that it`s missing or what`s your problem here?
I just noticed that the header is not defined in kernel 2.6 while porting a patch for the kernel 2.4 version of enet.c to kernel 2.6. The driver is still working, my bug report is just a hint for some small code cleanup;-)
arch 'ppc' will be removed from 2.6.27 so I don't think this needs fixing.