tools/power/x86/intel-speed-select: Implement CascadeLake-N help and command functions structures

CascadeLake-N only supports SST-BF and needs some of the perf-profile
commands, and the base-freq commands.

Add help functions, and create an empty command structures (the functions
will be implemented later in this patchset).  Call these functions
when running on CascadeLake-N.

Signed-off-by: Prarit Bhargava <prarit@redhat.com>
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>