UPSTREAM: coresight: perf: Refactor function free_event_data()

(Upstream commit f5200aa9831f38271c8104565fdcae4401658475).

Function free_event_data() is already busy and is bound to become
worse with the addition of CPU-wide trace scenarios.  As such spin
off a new function to strickly take care of the sink buffers.

Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Tested-by: Leo Yan <leo.yan@linaro.org>
Tested-by: Robert Walker <robert.walker@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Bug: 140266694
Change-Id: I7ed7be5f783cb9814ab3e0d760ca3501e53dbd3d
Signed-off-by: Yabin Cui <yabinc@google.com>