thermal: Fix compiler warning

The following warning is obtained when CONFIG_NET is not defined:

In file included from drivers/thermal/mvebu_thermal.c:27:0:
include/linux/thermal.h:254:12: warning: 'thermal_generate_netlink_event'
defined but not used [-Wunused-function]

This patch fixes the warning by properly inlining
thermal_generate_netlink_event().

Signed-off-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
diff --git a/include/linux/thermal.h b/include/linux/thermal.h
index f0bd7f9..fd7b8f3 100644
--- a/include/linux/thermal.h
+++ b/include/linux/thermal.h
@@ -251,7 +251,7 @@
 extern int thermal_generate_netlink_event(struct thermal_zone_device *tz,
 						enum events event);
 #else
-static int thermal_generate_netlink_event(struct thermal_zone_device *tz,
+static inline int thermal_generate_netlink_event(struct thermal_zone_device *tz,
 						enum events event)
 {
 	return 0;