MAINTAINERS: Add include/hw/openrisc/ to the OpenRISC section

hw/openrisc/ is already listed here, so we should mention
the folder for the headers here, too.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20231017154242.234133-1-thuth@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>

MAINTAINERS

@@ -295,6 +295,7 @@ S: Odd Fixes
 F: docs/system/openrisc/cpu-features.rst
 F: target/openrisc/
 F: hw/openrisc/
+F: include/hw/openrisc/
 F: tests/tcg/openrisc/
 
 PowerPC TCG CPUs