Incoporating feedback from bgregg:
Make per-cpu nature of output buffer be hidden and implicit. As such,
incoporate some rewriting into the definition of the PERF_OUTPUT.
Create two different macros to distinguish the perf_array (hardware
counters) from the perf_output (ring buffer) use cases.

Also, rename perf_output to perf_submit.
Signed-off-by: Brenden Blanco <bblanco@plumgrid.com>