Makefile: Correct TPL rule for OF_REAL

Correct an error in the tpl-dtb parameter to binman. At present the TPL
rule follows SPL but this is not correct, if TPL uses of-platdata, for
example.

Fixes: f99cbe4e867 ("fdt: Update Makefile rules with the new OF_REAL Kconfig")
Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
diff --git a/Makefile b/Makefile
index 299cd3f..194f93b 100644
--- a/Makefile
+++ b/Makefile
@@ -1314,7 +1314,7 @@
 		-a spl-bss-pad=$(if $(CONFIG_SPL_SEPARATE_BSS),,1) \
 		-a tpl-bss-pad=$(if $(CONFIG_TPL_SEPARATE_BSS),,1) \
 		-a spl-dtb=$(CONFIG_SPL_OF_REAL) \
-		-a tpl-dtb=$(CONFIG_SPL_OF_REAL) \
+		-a tpl-dtb=$(CONFIG_TPL_OF_REAL) \
 		$(BINMAN_$(@F))
 
 OBJCOPYFLAGS_u-boot.ldr.hex := -I binary -O ihex