Revert "arm64: Fix vdso-offsets.h dependency"

This reverts commit 90f777beb7.

While this commit was aimed at fixing the dependencies, with a large
make -j the vdso-offsets.h file is not generated, leading to build
failures.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

arch/arm64/kernel/vdso/Makefile

@@ -23,7 +23,7 @@ GCOV_PROFILE := n
 ccflags-y += -Wl,-shared
 
 obj-y += vdso.o
-extra-y += vdso.lds
+extra-y += vdso.lds vdso-offsets.h
 CPPFLAGS_vdso.lds += -P -C -U$(ARCH)
 
 # Force dependency (incbin is bad)
@@ -42,10 +42,11 @@ $(obj)/%.so: $(obj)/%.so.dbg FORCE
 gen-vdsosym := $(srctree)/$(src)/gen_vdso_offsets.sh
 quiet_cmd_vdsosym = VDSOSYM $@
 define cmd_vdsosym
-	$(NM) $< | $(gen-vdsosym) | LC_ALL=C sort > $@
+	$(NM) $< | $(gen-vdsosym) | LC_ALL=C sort > $@ && \
+	cp $@ include/generated/
 endef
 
-$(objtree)/include/generated/vdso-offsets.h: $(obj)/vdso.so.dbg FORCE
+$(obj)/vdso-offsets.h: $(obj)/vdso.so.dbg FORCE
 	$(call if_changed,vdsosym)
 
 # Assembly rules for the .S files