tools/power turbostat: modprobe msr, if needed

Some distros (Ubuntu) ship the msr driver as a module.
If turbosat is run as root on those systems, and discovers
that there is no /dev/cpu/cpu0/msr, it will now "modprobe msr"
for the user.

If not root, the modprobe attempt will fail, and turbostat will exit as before:

turbostat: no /dev/cpu/0/msr, Try "# modprobe msr" : No such file or directory

Signed-off-by: Len Brown <len.brown@intel.com>