kbuild: add dummy obj-y to create built-in.o

We are going to switch over to Kbuild in upcoming commits.

Each makefile must have non-empty obj- or obj-y
to generate built-in.o on Kbuild.
Signed-off-by: NMasahiro Yamada <yamada.m@jp.panasonic.com>

arch/arm/cpu/armv7/tegra114/Makefile

@@ -17,4 +17,5 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #
 
-obj- :=
+# necessary to create built-in.o
+obj- := __dummy__.o

arch/arm/cpu/armv7/tegra30/Makefile

@@ -17,4 +17,5 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #
 
-obj- :=
+# necessary to create built-in.o
+obj- := __dummy__.o

arch/nds32/cpu/n1213/Makefile

@@ -9,4 +9,7 @@
 # SPDX-License-Identifier:	GPL-2.0+
 #
 
+# necessary to create built-in.o
+obj- := __dummy__.o
+
 extra-y	= start.o

board/freescale/common/Makefile

@@ -13,7 +13,10 @@ MINIMAL=y
 endif
 endif
 
-ifndef MINIMAL
+ifdef MINIMAL
+# necessary to create built-in.o
+obj- := __dummy__.o
+else
 obj-$(CONFIG_FSL_CADMUS)	+= cadmus.o
 obj-$(CONFIG_FSL_VIA)		+= cds_via.o
 obj-$(CONFIG_FMAN_ENET)	+= fman.o

board/samsung/origen/Makefile

@@ -5,6 +5,9 @@
 #
 
 ifdef CONFIG_SPL_BUILD
+# necessary to create built-in.o
+obj- := __dummy__.o
+
 hostprogs-y := tools/mkorigenspl
 always := $(hostprogs-y)
 

board/samsung/smdkv310/Makefile

@@ -5,6 +5,9 @@
 #
 
 ifdef CONFIG_SPL_BUILD
+# necessary to create built-in.o
+obj- := __dummy__.o
+
 hostprogs-y := tools/mksmdkv310spl
 always := $(hostprogs-y)
 else

board/spear/common/Makefile

@@ -5,7 +5,10 @@
 # SPDX-License-Identifier:	GPL-2.0+
 #
 
-ifndef CONFIG_SPL_BUILD
+ifdef CONFIG_SPL_BUILD
+# necessary to create built-in.o
+obj- := __dummy__.o
+else
 obj-y	:= spr_misc.o
 obj-y	+= spr_lowlevel_init.o
 endif

board/spear/x600/Makefile

@@ -5,6 +5,9 @@
 # SPDX-License-Identifier:	GPL-2.0+
 #
 
-ifndef CONFIG_SPL_BUILD
+ifdef CONFIG_SPL_BUILD
+# necessary to create built-in.o
+obj- := __dummy__.o
+else
 obj-y	:= fpga.o x600.o
 endif