s390: add 'install' target to 'make help'

Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/Makefile

@@ -129,4 +129,8 @@ archclean:
 define archhelp
   echo  '* image           - Kernel image for IPL ($(boot)/image)'
   echo	'* bzImage         - Compressed kernel image for IPL ($(boot)/bzImage)'
+  echo	'  install         - Install kernel using'
+  echo	'                    (your) ~/bin/$(INSTALLKERNEL) or'
+  echo	'                    (distribution) /sbin/$(INSTALLKERNEL) or'
+  echo	'                    install to $$(INSTALL_PATH)'
 endef