tools/power/x86/intel-speed-select: Fix display for turbo-freq auto mode

When mailbox command for the turbo-freq enable fails, then don't display
result for auto-mode. When turbo-freq enable fails, there is no point
to set CPU priorities.

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