MAINTAINERS: ARM: at91: update my email address

Free Electrons is now Bootlin.
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

MAINTAINERS

@@ -1238,7 +1238,7 @@ F:	drivers/clk/at91
 
 ARM/ATMEL AT91RM9200, AT91SAM9 AND SAMA5 SOC SUPPORT
 M:	Nicolas Ferre <nicolas.ferre@microchip.com>
-M:	Alexandre Belloni <alexandre.belloni@free-electrons.com>
+M:	Alexandre Belloni <alexandre.belloni@bootlin.com>
 L:	linux-arm-kernel@lists.infradead.org (moderated for non-subscribers)
 W:	http://www.linux4sam.org
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/nferre/linux-at91.git