tools/power/x86/intel-speed-select: Increase string size

The current string size to print cpulist can accommodate upto 80
logical CPUs per package. But this limit is not enough. So increase
the string size. Also prevent buffer overflow, if the string size
reaches limit.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>