MSCC: add board support for the Luton based evaluation board

Adding the support for the Luton boards PCB91 which share common code with
the Ocelots boards, including board code, device tree and configuration.

Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>
diff --git a/MAINTAINERS b/MAINTAINERS
index d9de915..bb0a107 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -518,6 +518,7 @@
 M:	Horatiu Vultur <horatiu.vultur@microchip.com>
 S:	Maintained
 F:	arch/mips/mach-mscc/
+F:	arch/mips/dts/luton*
 F:	arch/mips/dts/mscc*
 F:	arch/mips/dts/ocelot*
 F:	board/mscc/