MAINTAINERS: update firmware loader entry

This email of 'ming.lei@canonical.com' isn't valid any more,
please remove the entry.
Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

MAINTAINERS

@@ -5110,7 +5110,6 @@ F:	include/uapi/linux/firewire*.h
 F:	tools/firewire/
 
 FIRMWARE LOADER (request_firmware)
-M:	Ming Lei <ming.lei@canonical.com>
 M:	Luis R. Rodriguez <mcgrof@kernel.org>
 L:	linux-kernel@vger.kernel.org
 S:	Maintained