MAINTAINERS: add Mao Han for CSKY

Signed-off-by: Guo Ren <ren_guo@c-sky.com>
Signed-off-by: Mao Han <han_mao@c-sky.com>

MAINTAINERS

@@ -9,6 +9,7 @@ Vineet Gupta <Vineet.Gupta1@synopsys.com>
 
 CSKY:
 Guo Ren <ren_guo@c-sky.com>
+Mao Han <han_mao@c-sky.com>
 
 MIPS:
 Matthew Fortune <Matthew.Fortune@imgtec.com>