kbuild: Simplify builds with CONFIG_OF_ALL_DTBS

We update 'always-y' based on CONFIG_OF_ALL_DTBS three times. It would be
far more straight forward if we rather update dtb-y to include all .dtb
files if CONFIG_OF_ALL_DTBS is enabled.
Acked-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Frank Rowand <frank.rowand@sony.com>
Tested-by: Frank Rowand <frank.rowand@sony.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/7fe7e5ef6ed75450ddf6c224b8adb53059e504e2.1615354376.git.viresh.kumar@linaro.org

scripts/Makefile.lib

@@ -73,14 +73,13 @@ always-y += $(userprogs-always-y) $(userprogs-always-m)
 
 # DTB
 # If CONFIG_OF_ALL_DTBS is enabled, all DT blobs are built
+dtb-$(CONFIG_OF_ALL_DTBS)       += $(dtb-)
+
 always-y			+= $(dtb-y)
-always-$(CONFIG_OF_ALL_DTBS)	+= $(dtb-)
 
 ifneq ($(CHECK_DTBS),)
 always-y += $(patsubst %.dtb,%.dt.yaml, $(dtb-y))
 always-y += $(patsubst %.dtbo,%.dt.yaml, $(dtb-y))
-always-$(CONFIG_OF_ALL_DTBS) += $(patsubst %.dtb,%.dt.yaml, $(dtb-))
-always-$(CONFIG_OF_ALL_DTBS) += $(patsubst %.dtbo,%.dt.yaml, $(dtb-))
 endif
 
 # Add subdir path