Add mpc7448hpc2 maintainer information

Signed-off-by: Roy Zang <tie-fei.zang@freescale.com>

MAINTAINERS

@@ -420,6 +420,10 @@ Guennadi Liakhovetski <g.liakhovetski@gmx.de>
 
 	linkstation	MPC8241
 
+Roy Zang <tie-fei.zang@freescale.com>
+
+	mpc7448hpc2	MPC7448
+
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 Unknown / orphaned boards: