x86/boot/build: Add phony targets in arch/x86/boot/Makefile to PHONY

These targets are correctly added to PHONY in arch/x86/Makefile, but
not in arch/x86/boot/Makefile. Thus, with a file 'install' in the top
directory, 'make install' does nothing:

  $ touch install
  $ make install
  make[1]: 'install' is up to date.

Add them to the PHONY targets in the boot Makefile too.

 [ bp: Massage. ]

Signed-off-by: Masahiro Yamada <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]
diff --git a/arch/x86/boot/Makefile b/arch/x86/boot/Makefile
index f1bf4a7..4c53556 100644
--- a/arch/x86/boot/Makefile
+++ b/arch/x86/boot/Makefile
@@ -128,6 +128,8 @@
 cmd_genimage = sh $(srctree)/$(src)/genimage.sh $2 $3 $(obj)/bzImage \
 			$(obj)/mtools.conf '$(image_cmdline)' $(FDINITRD)
 
+PHONY += bzdisk fdimage fdimage144 fdimage288 isoimage bzlilo install
+
 # This requires write access to /dev/fd0
 bzdisk: $(obj)/bzImage $(obj)/mtools.conf
 	$(call cmd,genimage,bzdisk,/dev/fd0)