[POWERPC] Add co-maintainer for PowerPC MPC52xx platform

Added at the request of Sylvain Munaut.
Signed-off-by: NGrant Likely <grant.likely@secretlab.ca>
Signed-off-by: NSylvain Munaut <tnt@246tnt.com>

MAINTAINERS

@@ -2288,6 +2288,8 @@ S:	Maintained
 LINUX FOR POWERPC EMBEDDED MPC52XX
 P:	Sylvain Munaut
 M:	tnt@246tNt.com
+P:	Grant Likely
+M:	grant.likely@secretlab.ca
 W:	http://www.246tNt.com/mpc52xx/
 W:	http://www.penguinppc.org/
 L:	linuxppc-dev@ozlabs.org