arch: vdso: add vdso linker script to 'targets' instead of extra-y

The vdso linker script is preprocessed on demand.
Adding it to 'targets' is enough to include the .cmd file.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Greentime Hu <green.hu@gmail.com>
diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile
index 45d5cfe..7cd8aaf 100644
--- a/arch/arm64/kernel/vdso/Makefile
+++ b/arch/arm64/kernel/vdso/Makefile
@@ -54,7 +54,7 @@
 GCOV_PROFILE := n
 
 obj-y += vdso.o
-extra-y += vdso.lds
+targets += vdso.lds
 CPPFLAGS_vdso.lds += -P -C -U$(ARCH)
 
 # Force dependency (incbin is bad)