MAINTAINERS: add documentation file for Microchip EIC section

Add documentation file to Microchip EIC section.
Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Link: https://lore.kernel.org/r/20230523070637.224476-3-claudiu.beznea@microchip.comSigned-off-by: Rob Herring <robh@kernel.org>

MAINTAINERS

@@ -13704,6 +13704,7 @@ MICROCHIP EIC DRIVER
 M:	Claudiu Beznea <claudiu.beznea@microchip.com>
 L:	linux-arm-kernel@lists.infradead.org (moderated for non-subscribers)
 S:	Supported
+F:	Documentation/devicetree/bindings/interrupt-controller/microchip,sama7g5-eic.yaml
 F:	drivers/irqchip/irq-mchp-eic.c
 
 MICROCHIP I2C DRIVER