tools/power/x86/intel-speed-select: Show error for invalid CPUs in the options

When --cpu or -c is used to specify target CPUs and non of them are valid,
display error.

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