cpufreq: intel_pstate: Do not update global.turbo_disabled after initialization

cpufreq: intel_pstate: Do not update global.turbo_disabled after initialization

[ Upstream commit 0940f1a8011fd69be5082015068e0dc31c800c20 ]

The global.turbo_disabled is updated quite often, especially in the
passive mode in which case it is updated every time the scheduler calls
into the driver.  However, this is generally not necessary and it adds
MSR read overhead to scheduler code paths (and that particular MSR is
slow to read).

For this reason, make the driver read MSR_IA32_MISC_ENABLE_TURBO_DISABLE
just once at the cpufreq driver registration time and remove all of the
in-flight updates of global.turbo_disabled.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Stable-dep-of: ac4e04d9e378 ("cpufreq: intel_pstate: Unchecked MSR aceess in legacy mode")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>