Makefile: Correct the binman rule

This currently uses if_changed on a phony target. Use a real file as the
target and add FORCE at the end, as required. Drop the 'inputs' phony
since it is not needed.

Signed-off-by: Simon Glass <sjg@chromium.org>

Makefile

@@ -1108,18 +1108,15 @@ define deprecated
 
 endef
 
-PHONY += inputs
-inputs: $(INPUTS-y)
-
-all: .binman_stamp inputs
+# Timestamp file to make sure that binman always runs
+.binman_stamp: $(INPUTS-y) FORCE
 ifeq ($(CONFIG_BINMAN),y)
 	$(call if_changed,binman)
 endif
-
-# Timestamp file to make sure that binman always runs
-.binman_stamp: FORCE
 	@touch $@
 
+all: .binman_stamp
+
 ifeq ($(CONFIG_DEPRECATED),y)
 	$(warning "You have deprecated configuration options enabled in your .config! Please check your configuration.")
 endif