board: powerpc: convert makefiles to Kbuild style

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Cc: Wolfgang Denk <wd@denx.de>
Cc: Kim Phillips <kim.phillips@freescale.com>
Cc: York Sun <yorksun@freescale.com>
Cc: Stefan Roese <sr@denx.de>
diff --git a/board/freescale/p1_p2_rdb_pc/Makefile b/board/freescale/p1_p2_rdb_pc/Makefile
index 202b4a5..8e20073 100644
--- a/board/freescale/p1_p2_rdb_pc/Makefile
+++ b/board/freescale/p1_p2_rdb_pc/Makefile
@@ -4,10 +4,6 @@
 # SPDX-License-Identifier:	GPL-2.0+
 #
 
-include $(TOPDIR)/config.mk
-
-LIB    = $(obj)lib$(BOARD).o
-
 MINIMAL=
 
 ifdef CONFIG_SPL_BUILD
@@ -18,32 +14,16 @@
 
 ifdef MINIMAL
 
-COBJS-y	+= spl_minimal.o tlb.o law.o
+obj-y	+= spl_minimal.o tlb.o law.o
 
 else
 ifdef CONFIG_SPL_BUILD
 COBJS-y += spl.o
 endif
 
-COBJS-y        += $(BOARD).o
-COBJS-y        += ddr.o
-COBJS-y        += law.o
-COBJS-y        += tlb.o
+obj-y        += p1_p2_rdb_pc.o
+obj-y        += ddr.o
+obj-y        += law.o
+obj-y        += tlb.o
 
 endif
-
-SRCS   := $(SOBJS:.o=.S) $(COBJS-y:.o=.c)
-OBJS   := $(addprefix $(obj),$(COBJS-y))
-SOBJS  := $(addprefix $(obj),$(SOBJS))
-
-$(LIB):	$(obj).depend $(OBJS) $(SOBJS)
-	$(call cmd_link_o_target, $(OBJS))
-
-#########################################################################
-
-# defines $(obj).depend target
-include $(SRCTREE)/rules.mk
-
-sinclude $(obj).depend
-
-#########################################################################