KernelBenchmarksTrackUtilisation: Add more stats

For each thread also track number of times scheduled, number of kernel
entries and amount of cycles spent inside the kernel. Also add
core-wide totals for each.

Signed-off-by: Kent McLeod <Kent.Mcleod@data61.csiro.au>

KernelBenchmarksTrackUtilisation: refactor reset

Change benchmark_track_reset_utilisation to take a tcb object parameter
so that the function is more widely applicable.

Signed-off-by: Kent McLeod <Kent.Mcleod@data61.csiro.au>

KernelBenchmarksTrackUtilisation: Fix for SMP

Create per-node global definitions for utilization variables.
This enables the tracking to more cleanly work on SMP configurations.
As resetting and starting the counters via SysBenchmarkResetLog only
updates the counters of the current thread and idle thread on the
current node it was not possible to accurately record utilization
statistics across multiple nodes. Now each node can have its tracking
independently started, stopped and queried. It is possible to add
additional syscalls in the future for doing this for all nodes in a
single syscall.

Signed-off-by: Kent McLeod <Kent.Mcleod@data61.csiro.au>

Convert license tags to SPDX identifiers

This commit also converts our own copyright headers to directly use
SPDX, but leaves all other copyright header intact, only adding the
SPDX ident. As far as possible this commit also merges multiple
Data61 copyright statements/headers into one for consistency.

style: set code width to 120

benchmark: Use ENABLE_SMP_SUPPORT helper definition

benchmark: support reading out idle cpu time on remote cpu

Fixes #68

Benchmark: Pack arch-independent benchmark-related files into separate directories