MAINTAINERS: add Microchip mpfs mssio driver/bindings to entry

Add the new mssio driver and bindings to the existing entry
for Microchip RISC-V devices.

Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Linus Walleij <linusw@kernel.org>

Author: ConchuOD

MAINTAINERS

@@ -22458,6 +22458,7 @@ F:	Documentation/devicetree/bindings/i2c/microchip,corei2c.yaml
 F:	Documentation/devicetree/bindings/mailbox/microchip,mpfs-mailbox.yaml
 F:	Documentation/devicetree/bindings/net/can/microchip,mpfs-can.yaml
 F:	Documentation/devicetree/bindings/pinctrl/microchip,mpfs-pinctrl-iomux0.yaml
+F:	Documentation/devicetree/bindings/pinctrl/microchip,mpfs-pinctrl-mssio.yaml
 F:	Documentation/devicetree/bindings/pinctrl/microchip,pic64gx-pinctrl-gpio2.yaml
 F:	Documentation/devicetree/bindings/pwm/microchip,corepwm.yaml
 F:	Documentation/devicetree/bindings/riscv/microchip.yaml
@@ -22473,6 +22474,7 @@ F:	drivers/i2c/busses/i2c-microchip-corei2c.c
 F:	drivers/mailbox/mailbox-mpfs.c
 F:	drivers/pci/controller/plda/pcie-microchip-host.c
 F:	drivers/pinctrl/microchip/pinctrl-mpfs-iomux0.c
+F:	drivers/pinctrl/microchip/pinctrl-mpfs-mssio.c
 F:	drivers/pinctrl/microchip/pinctrl-pic64gx-gpio2.c
 F:	drivers/pwm/pwm-microchip-core.c
 F:	drivers/reset/reset-mpfs.c