The 'intel_pstate' driver does not allow the EPP to be set to anything
but 'performance' when the scaling governor is set to 'performance',
previously auto-cpufreq when the scaling-governor was set to
'performance' tried to set the EPP to 'balance-performance'
which caused a spam of write error messages in journalctl in system
with 'intel_pstate' drivers.
This is an intended behavior, since according to the [kernel documentation](https://docs.kernel.org/admin-guide/pm/intel_pstate.html#hwp-performance)
when HWP is enabled[(which is enabled by default during boot with supported processors)](https://docs.kernel.org/admin-guide/pm/intel_pstate.html#active-mode-with-hwp)
and scaling governor is set to performance the processor’s internal
P-state selection logic is expected to focus entirely on performance.
And this will override the EPP setting and reject any value different from 0 (“performance”).
This commit just changes the 'balance-performance' EPP preference in
set_performance() to 'performance'. Which fixes the spam issue.

intel_pstate/staus to make sure the condition only applies when "active"