tools: build mkeficapsule with tools-only_defconfig

Add CONFIG_TOOLS_MKEFICAPSULE. Then we want to always build mkeficapsule
if tools-only_defconfig is used.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/Makefile b/tools/Makefile
index 1763f44..766c067 100644
--- a/tools/Makefile
+++ b/tools/Makefile
@@ -238,8 +238,7 @@
 hostprogs-$(CONFIG_ASN1_COMPILER)	+= asn1_compiler
 HOSTCFLAGS_asn1_compiler.o = -idirafter $(srctree)/include
 
-mkeficapsule-objs	:= mkeficapsule.o $(LIBFDT_OBJS)
-hostprogs-$(CONFIG_EFI_HAVE_CAPSULE_SUPPORT) += mkeficapsule
+hostprogs-$(CONFIG_TOOLS_MKEFICAPSULE) += mkeficapsule
 
 # We build some files with extra pedantic flags to try to minimize things
 # that won't build on some weird host compiler -- though there are lots of