MAINTAINERS: add ixp4xx_crypto to the right arch list

drivers/crypto/ixp4xx_crypto.c is missing in the IXP4XX arch file list.
Signed-off-by: NCorentin Labbe <clabbe@baylibre.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

MAINTAINERS

@@ -1972,6 +1972,7 @@ F:	Documentation/devicetree/bindings/interrupt-controller/intel,ixp4xx-interrupt
 F:	Documentation/devicetree/bindings/timer/intel,ixp4xx-timer.yaml
 F:	arch/arm/mach-ixp4xx/
 F:	drivers/clocksource/timer-ixp4xx.c
+F:	drivers/crypto/ixp4xx_crypto.c
 F:	drivers/gpio/gpio-ixp4xx.c
 F:	drivers/irqchip/irq-ixp4xx.c
 F:	include/linux/irqchip/irq-ixp4xx.h