MAINTAINERS: add include/dt-bindings/thermal to THERMAL

Maintainers of the directory Documentation/devicetree/bindings/thermal
are also the maintainers of the corresponding directory
include/dt-bindings/thermal.

Add the file entry for include/dt-bindings/thermal to the appropriate
section in MAINTAINERS.
Signed-off-by: NLukas Bulwahn <lukas.bulwahn@gmail.com>
Link: https://lore.kernel.org/r/20220613124309.28790-1-lukas.bulwahn@gmail.comSigned-off-by: NDaniel Lezcano <daniel.lezcano@linaro.org>

MAINTAINERS

@@ -19586,6 +19586,7 @@ F:	Documentation/ABI/testing/sysfs-class-thermal
 F:	Documentation/devicetree/bindings/thermal/
 F:	Documentation/driver-api/thermal/
 F:	drivers/thermal/
+F:	include/dt-bindings/thermal/
 F:	include/linux/cpu_cooling.h
 F:	include/linux/thermal.h
 F:	include/uapi/linux/thermal.h