thermal: int3400: Fix reading of current_uuid for active policy

When the current_uuid attribute is set to the active policy UUID,
reading back the same attribute is returning "INVALID" instead of
the active policy UUID on some platforms before Ice Lake.

In platforms before Ice Lake, firmware provides a list of supported
thermal policies. In this case, user space can select any of the
supported thermal policies via a write to attribute "current_uuid".

In commit c7ff297 ("thermal: int340x: Update OS policy capability
handshake")', the OS policy handshake was updated to support Ice Lake
and later platforms and it treated priv->current_uuid_index=0 as
invalid. However, priv->current_uuid_index=0 is for the active policy,
only priv->current_uuid_index=-1 is invalid.

Fix this issue by updating the priv->current_uuid_index check.

Fixes: c7ff297 ("thermal: int340x: Update OS policy capability handshake")
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Cc: 5.18+ <stable@vger.kernel.org> # 5.18+
Link: https://patch.msgid.link/20241114200213.422303-1-srinivas.pandruvada@linux.intel.com
[ rjw: Subject and changelog edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Author: spandruvada

drivers/thermal/intel/int340x_thermal/int3400_thermal.c

@@ -137,7 +137,7 @@ static ssize_t current_uuid_show(struct device *dev,
 	struct int3400_thermal_priv *priv = dev_get_drvdata(dev);
 	int i, length = 0;
 
-	if (priv->current_uuid_index > 0)
+	if (priv->current_uuid_index >= 0)
 		return sprintf(buf, "%s\n",
 			       int3400_thermal_uuids[priv->current_uuid_index]);