cpufreq: intel_pstate: Allow repeated intel_pstate disable

Repeated intel_pstate disables currently return an error, adding unnecessary
complexity to userspace scripts which must first read the current state and
conditionally write 'off'.

Make repeated intel_pstate disables a no-op.

Signed-off-by: Fabio M. De Francesco <fabio.m.de.francesco@linux.intel.com>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Link: https://patch.msgid.link/20260219181600.16388-1-fabio.m.de.francesco@linux.intel.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Author: fdefranc

drivers/cpufreq/intel_pstate.c

@@ -3472,7 +3472,7 @@ static int intel_pstate_update_status(const char *buf, size_t size)
 {
 	if (size == 3 && !strncmp(buf, "off", size)) {
 		if (!intel_pstate_driver)
-			return -EINVAL;
+			return 0;
 
 		if (hwp_active)
 			return -EBUSY;