x86: Use X86_16BIT_INIT instead of X86_RESET_VECTOR

Use this new option to control the location of 16-bit init. This will allow
us to place this in SPL if needed.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/Makefile b/Makefile
index d3222a0..ed817f5 100644
--- a/Makefile
+++ b/Makefile
@@ -883,7 +883,7 @@
 	$(call if_changed,objcopy)
 
 OBJCOPYFLAGS_u-boot-nodtb.bin := -O binary \
-		$(if $(CONFIG_X86_RESET_VECTOR),-R .start16 -R .resetvec)
+		$(if $(CONFIG_X86_16BIT_INIT),-R .start16 -R .resetvec)
 
 binary_size_check: u-boot-nodtb.bin FORCE
 	@file_size=$(shell wc -c u-boot-nodtb.bin | awk '{print $$1}') ; \
@@ -1077,8 +1077,9 @@
 cmd_ldr = $(LD) $(LDFLAGS_$(@F)) \
 	       $(filter-out FORCE,$^) -o $@
 
-u-boot.rom: u-boot-x86-16bit.bin u-boot.bin FORCE \
-		$(if $(CONFIG_HAVE_REFCODE),refcode.bin)
+u-boot.rom: u-boot-x86-16bit.bin u-boot.bin \
+		$(if $(CONFIG_SPL_X86_16BIT_INIT),spl/u-boot-spl.bin) \
+		$(if $(CONFIG_HAVE_REFCODE),refcode.bin) FORCE
 	$(call if_changed,binman)
 
 OBJCOPYFLAGS_u-boot-x86-16bit.bin := -O binary -j .start16 -j .resetvec