percpu: move arch XX_PER_CPU_XX definitions into linux/percpu.h

- Special consideration for IA64: Add the ability to specify
  arch specific per cpu flags

- remove .data.percpu attribute from DEFINE_PER_CPU for non-smp case.

The arch definitions are all the same. So move them into linux/percpu.h.

We cannot move DECLARE_PER_CPU since some include files just include
asm/percpu.h to avoid include recursion problems.

Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Mike Travis <travis@sgi.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>