68360enet: Remove Kconfig/Makefile references

68360enet.c no longer exists, and from the research, it appears that
68360enet.c became fec.c back in 2004.  The Kconfig and Makefile
references were never cleaned up.  This patch removes this "dead"
references.

Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>