Makefile: Rename ALL-y to INPUTS-y

When binman is in use, most of the targets built by the Makefile are
inputs to binman. We then need a final rule to run binman to produce the
final outputs.

Rename the variable to indicate this, and add a new 'inputs' target.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/arch/arm/mach-rmobile/Makefile b/arch/arm/mach-rmobile/Makefile
index a3fdcc3..3206bce 100644
--- a/arch/arm/mach-rmobile/Makefile
+++ b/arch/arm/mach-rmobile/Makefile
@@ -84,5 +84,5 @@
 
 # if srec_cat is present build u-boot-spl.scif by default
 has_srec_cat = $(call try-run,srec_cat -VERSion,y,n)
-ALL-$(has_srec_cat) += u-boot-spl.scif
+INPUTS-$(has_srec_cat) += u-boot-spl.scif
 CLEAN_FILES += u-boot-spl.scif