cpufreq/amd-pstate: Allow writes to dynamic_epp when state isn't modified

Writing the current "dynamic_epp" state to sysfs fails with -EINVAL even
though the desired result was achieved. Allow writes to "dynamic_epp"
that does not modify the state.

Fixes: e30ca6d ("cpufreq/amd-pstate: Add dynamic energy performance preference")
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com>
Link: https://lore.kernel.org/r/20260508051748.10484-4-kprateek.nayak@amd.com
Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>

Author: kudureranganath

drivers/cpufreq/amd-pstate.c

@@ -1832,8 +1832,9 @@ static ssize_t dynamic_epp_store(struct device *a, struct device_attribute *b,
 		return -EINVAL;
 	}
 
+	/* Nothing to do */
 	if (dynamic_epp == enabled)
-		return -EINVAL;
+		return count;
 
 	/* reinitialize with desired dynamic EPP value */
 	dynamic_epp = enabled;