MAINTAINERS: Mark Andrew as M: for ASPEED MACHINE SUPPORT

From discussion in [1] and in-person with Joel, flip my entry from R:
to M:.

Link: https://lore.kernel.org/all/CACPK8Xe8yZLXzEQPp=1D2f0TsKA7hBZG=pHHW6U51FMpp_BiRQ@mail.gmail.com/ [1]
Cc: Joel Stanley <joel@jms.id.au>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: soc@lists.linux.dev
Cc: linux-aspeed@lists.ozlabs.org
Cc: linux-arm-kernel@lists.infradead.org
Signed-off-by: Andrew Jeffery <andrew@codeconstruct.com.au>
Acked-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Author: amboar

MAINTAINERS

@@ -2284,7 +2284,7 @@ F:	drivers/irqchip/irq-aspeed-i2c-ic.c
 
 ARM/ASPEED MACHINE SUPPORT
 M:	Joel Stanley <joel@jms.id.au>
-R:	Andrew Jeffery <andrew@codeconstruct.com.au>
+M:	Andrew Jeffery <andrew@codeconstruct.com.au>
 L:	linux-arm-kernel@lists.infradead.org (moderated for non-subscribers)
 L:	linux-aspeed@lists.ozlabs.org (moderated for non-subscribers)
 S:	Supported