perf tools: Add a place to put kernel config fragments for test runs

Defconfig doesn't give full coverage for a perf test run, so these can
be merged with defconfig to do so. It's not complete yet, but is a
starting point as a place to add to when a specific test needs something
extra to run.

Signed-off-by: James Clark <james.clark@arm.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Aishwarya.TCV@arm.com
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Mark Brown <broonie@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230628105303.4053478-2-james.clark@arm.com


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>