MIPS: Alchemy: move boards over to obj-y

Preparatory step for moving Alchemy over to new  MIPS Platform
build system support.

Signed-off-by: Manuel Lauss <manuel.lauss@googlemail.com>
To: Linux-MIPS <linux-mips@linux-mips.org>
Patchwork: https://patchwork.linux-mips.org/patch/1318/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/alchemy/mtx-1/Makefile

@@ -6,7 +6,6 @@
 # Makefile for 4G Systems MTX-1 board.
 #
 
-lib-y := init.o board_setup.o
-obj-y := platform.o
+obj-y += init.o board_setup.o platform.o
 
 EXTRA_CFLAGS += -Werror

arch/mips/alchemy/xxs1500/Makefile

@@ -5,6 +5,6 @@
 # Makefile for MyCable XXS1500 board.
 #
 
-lib-y := init.o board_setup.o platform.o
+obj-y += init.o board_setup.o platform.o
 
 EXTRA_CFLAGS += -Werror