Revert "tracing: Move pipe reference to trace array instead of current_tracer"

This reverts commit 43e172e3 which is
commit 7ef282e05132d56b6f6b71e3873f317664bea78b upstream.

This is being reverted as is can cause some crc changes in modversions
due to the changes in trace.h.

From the description of the patch itself:
	This is marked as "Fixes" but is more of a clean up than a true fix.
	Backport if you want, but its not critical.

Bug: 161946584
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I781e50e6ebe6a2d09c3a4ec2703e7bdbffe8e632