ia64: move nr-irqs.h to include/generated

Avoid generating files in the now deprecated asm-ia64 dir
Simplified the logic in the Makefile when editing stuff in the area

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Michal Marek <mmarek@suse.cz>

arch/ia64/Makefile

diff --git a/arch/ia64/Makefile b/arch/ia64/Makefile
index e7cbaa0..475e272 100644
--- a/arch/ia64/Makefile
+++ b/arch/ia64/Makefile
@@ -103,4 +103,4 @@
 PHONY += make_nr_irqs_h FORCE
 
 make_nr_irqs_h: FORCE
-	$(Q)$(MAKE) $(build)=arch/ia64/kernel include/asm-ia64/nr-irqs.h
+	$(Q)$(MAKE) $(build)=arch/ia64/kernel include/generated/nr-irqs.h