platform/x86: intel-wmi-thunderbolt: Add dynamic debugging

Some users have been reporting issues with thunderbolt being turned off
before fully initialized. This is suspected to be caused by userspace
turning off the Thunderbolt controller using intel-wmi-thunderbolt
prematurely.

Userspace has already made some mitigations for this situation:
https://github.com/hughsie/fwupd/commit/ef6f1d76983c9b66
https://github.com/hughsie/fwupd/commit/c07ce5b4889a5384

To allow easier debugging of this situation add output that can be turned
on with dynamic debugging to better root cause this problem.

BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=199631
BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=201227
Suggested-by: Mika Westerberg <mika.westerberg@intel.com>
Signed-off-by: Mario Limonciello <mario.limonciello@dell.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>

drivers/platform/x86/intel-wmi-thunderbolt.c

@@ -30,12 +30,16 @@ static ssize_t force_power_store(struct device *dev,
 	input.length = sizeof(u8);
 	input.pointer = &mode;
 	mode = hex_to_bin(buf[0]);
+	dev_dbg(dev, "force_power: storing %#x\n", mode);
 	if (mode == 0 || mode == 1) {
 		status = wmi_evaluate_method(INTEL_WMI_THUNDERBOLT_GUID, 0, 1,
 					     &input, NULL);
-		if (ACPI_FAILURE(status))
+		if (ACPI_FAILURE(status)) {
+			dev_dbg(dev, "force_power: failed to evaluate ACPI method\n");
 			return -ENODEV;
+		}
 	} else {
+		dev_dbg(dev, "force_power: unsupported mode\n");
 		return -EINVAL;
 	}
 	return count;