MAINTAINERS: Update brcmstb entry

We have not heard back from Marc in a while, since we last asked him to
ack/nack this change here: https://lkml.org/lkml/2015/1/14/1004

This was back in January, we are in the 3.21^W4.1 merge window now, so,
as outlined in this email thread, remove him from the MAINTAINERS list
now.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>

MAINTAINERS

@@ -2169,7 +2169,6 @@ S:	Maintained
 F:	drivers/usb/gadget/udc/bcm63xx_udc.*
 
 BROADCOM BCM7XXX ARM ARCHITECTURE
-M:	Marc Carino <marc.ceeeee@gmail.com>
 M:	Brian Norris <computersforpeace@gmail.com>
 M:	Gregory Fong <gregory.0xf0@gmail.com>
 M:	Florian Fainelli <f.fainelli@gmail.com>