MIPS: STB22x: Move boards over to obj-y

Preparatory cleanup for moving Alchemy over to new  MIPS Platform build
system support.
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

arch/mips/Makefile

@@ -194,9 +194,9 @@ include $(srctree)/arch/mips/Kbuild.platforms
 # NXP STB225
 core-$(CONFIG_SOC_PNX833X)		+= arch/mips/pnx833x/common/
 cflags-$(CONFIG_SOC_PNX833X)	+= -Iarch/mips/include/asm/mach-pnx833x
-libs-$(CONFIG_NXP_STB220)		+= arch/mips/pnx833x/stb22x/
+core-$(CONFIG_NXP_STB220)		+= arch/mips/pnx833x/stb22x/
 load-$(CONFIG_NXP_STB220)		+= 0xffffffff80001000
-libs-$(CONFIG_NXP_STB225)		+= arch/mips/pnx833x/stb22x/
+core-$(CONFIG_NXP_STB225)		+= arch/mips/pnx833x/stb22x/
 load-$(CONFIG_NXP_STB225)		+= 0xffffffff80001000
 
 #

arch/mips/pnx833x/stb22x/Makefile

-lib-y := board.o
+obj-y := board.o
 
 EXTRA_CFLAGS += -Werror