kbuild: Fix dependencies for final vmlinux link

The if_changed directive is useless against phony targets.

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Fixes: 2441e78b1919 ("kbuild: better abstract vmlinux sequential prerequisites")
Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: Michal Marek <mmarek@suse.cz>

Makefile

@@ -953,7 +953,7 @@ include/generated/autoksyms.h: FORCE
       cmd_link-vmlinux = $(CONFIG_SHELL) $< $(LD) $(LDFLAGS) $(LDFLAGS_vmlinux)
 quiet_cmd_link-vmlinux = LINK    $@
 
-vmlinux: scripts/link-vmlinux.sh vmlinux_prereq FORCE
+vmlinux: scripts/link-vmlinux.sh vmlinux_prereq $(vmlinux-deps) FORCE
 	+$(call if_changed,link-vmlinux)
 
 # Build samples along the rest of the kernel