tools/power/x86/intel-speed-select: Improve error display for base-freq feature

This change adds improved error display and handling for commands related
to base-freq feature. The changes include:
- Replace perror/fprintf with helpful error message
- Error for not specifying TDP level when required
- For CLX show help which shows limitation

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