[IA64] Fix include dependency in asm/irqflags.h

asm/kregs.h isn't always included first, so we need an explicit include.

[Fix build breakage introduced by f21afc25f9ed45b8ffe200d0f071b0caec3ed2ef
 smp.h: Use local_irq_{save,restore}() in !SMP version of on_each_cpu().]

Signed-off-by: David Daney <david.daney@cavium.com>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Merge tag 'please-pull-fixia64' of git://git.kernel.org/pub/scm/linux/kernel/git/aegl/linux

Pull ia64 build fix from Tony Luck:
 "Fix ia64 build breakage by adding newly needed #include"

We're still debating the patch that caused the build breakage, but this
fix seems like a good idea regardless of how that ends up being handled.

* tag 'please-pull-fixia64' of git://git.kernel.org/pub/scm/linux/kernel/git/aegl/linux:
  [IA64] Fix include dependency in asm/irqflags.h