The install target should not depend on any build artifact.
The reason is explained in commit 
19514fc665ff ("arm, kbuild: make
"make install" not depend on vmlinux").
Change the PowerPC installation code in a similar way.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210729141937.445051-2-masahiroy@kernel.org
        $(Q)rm -f $@; ln $< $@
 
 # Only install the vmlinux
-install: $(CONFIGURE) $(addprefix $(obj)/, $(image-y))
+install:
        sh -x $(srctree)/$(src)/install.sh "$(KERNELRELEASE)" vmlinux System.map "$(INSTALL_PATH)"
 
 PHONY += install
 
 # Bail with error code if anything goes wrong
 set -e
 
+verify () {
+       if [ ! -f "$1" ]; then
+               echo ""                                                   1>&2
+               echo " *** Missing file: $1"                              1>&2
+               echo ' *** You need to run "make" before "make install".' 1>&2
+               echo ""                                                   1>&2
+               exit 1
+       fi
+}
+
+# Make sure the files actually exist
+verify "$2"
+verify "$3"
+
 # User may have a custom install script
 
 if [ -x ~/bin/${INSTALLKERNEL} ]; then exec ~/bin/${INSTALLKERNEL} "$@"; fi