MAINTAINERS: USB: change maintainer for Microchip USBA gadget driver

Hand over this USB gadget driver to Cristian: atmel_usba.
Signed-off-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

MAINTAINERS

@@ -2551,7 +2551,7 @@ F:	drivers/misc/atmel_tclib.c
 F:	drivers/clocksource/tcb_clksrc.c
 
 ATMEL USBA UDC DRIVER
-M:	Nicolas Ferre <nicolas.ferre@microchip.com>
+M:	Cristian Birsan <cristian.birsan@microchip.com>
 L:	linux-arm-kernel@lists.infradead.org (moderated for non-subscribers)
 S:	Supported
 F:	drivers/usb/gadget/udc/atmel_usba_udc.*