powerpc: fixup hard_irq_disable semantics

This patch renames the raw hard_irq_{enable,disable} into
__hard_irq_{enable,disable} and introduces a higher level hard_irq_disable()
function that can be used by any code to enforce that IRQs are fully disabled,
not only lazy disabled.

The difference with the __ versions is that it will update some per-processor
fields so that the kernel keeps track and properly re-enables them in the next
local_irq_disable();

This prepares powerpc for my next patch that introduces hard_irq_disable()
generically.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Paul Mackerras <paulus@samba.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/powerpc/kernel/swsusp.c

@@ -36,8 +36,4 @@ void restore_processor_state(void)
 #ifdef CONFIG_PPC32
 	set_context(current->active_mm->context.id, current->active_mm->pgd);
 #endif
-
-#ifdef CONFIG_PPC64
-	hard_irq_enable();
-#endif
 }