net: Temporarily backout SKB sources tracer.

net: Temporarily backout SKB sources tracer.

Steven Rostedt has suggested that Neil work with the tracing
folks, trying to use TRACE_EVENT as the mechanism for
implementation.  And if that doesn't workout we can investigate
other solutions such as that one which was tried here.

This reverts the following 2 commits:

5a165657bef7c47e5ff4cd138f7758ef6278e87b
("net: skb ftracer - Add config option to enable new ftracer (v3)")

9ec04da7489d2c9ae01ea6e9b5fa313ccf3d35fb
("net: skb ftracer - Add actual ftrace code to kernel (v3)")

Signed-off-by: David S. Miller <davem@davemloft.net>