There is a corner case that if the intel_pstate driver fails to be
registered (might be due to invalid MSR access) and acpi_cpufreq
takse over, the intel_pstate sysfs interface is still populated
which may confuse user space (turbostat for example):

grep . /sys/devices/system/cpu/cpu0/cpufreq/scaling_driver
acpi-cpufreq

grep . /sys/devices/system/cpu/intel_pstate/*
/sys/devices/system/cpu/intel_pstate/max_perf_pct:0
/sys/devices/system/cpu/intel_pstate/min_perf_pct:0
grep: /sys/devices/system/cpu/intel_pstate/no_turbo: Resource temporarily unavailable
grep: /sys/devices/system/cpu/intel_pstate/num_pstates: Resource temporarily unavailable
/sys/devices/system/cpu/intel_pstate/status:off
grep: /sys/devices/system/cpu/intel_pstate/turbo_pct: Resource temporarily unavailable

The mere presence of the intel_pstate sysfs interface does not mean
that intel_pstate is in use (for example, echo "off" to "status"),
but it should not be created in the failing case.

Fix this issue by deleting the intel_pstate sysfs if the driver
registration fails.
Reported-by: Wendy Wang <wendy.wang@intel.com>
Suggested-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com
[ rjw: Refactor code to avoid jumps, change function name, changelog edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>