tools/power/turbostat: Read energy_perf_bias from sysfs

... instead of poking at the MSR directly.

Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Len Brown <lenb@kernel.org>
Cc: linux-pm@vger.kernel.org
Link: https://lkml.kernel.org/r/20201029190259.3476-3-bp@alien8.de