ia64/cpu: Mark play_dead() __noreturn

play_dead() doesn't return.  Annotate it as such.  By extension this
also makes arch_cpu_idle_dead() noreturn.
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Link: https://lore.kernel.org/r/7575bb38417bd8bcb5be980443f99cab29319342.1676358308.git.jpoimboe@kernel.orgSigned-off-by: Josh Poimboeuf <jpoimboe@kernel.org>

arch/ia64/kernel/process.c

@@ -201,7 +201,7 @@ __setup("nohalt", nohalt_setup);
 
 #ifdef CONFIG_HOTPLUG_CPU
 /* We don't actually take CPU down, just spin without interrupts. */
-static inline void play_dead(void)
+static inline void __noreturn play_dead(void)
 {
 	unsigned int this_cpu = smp_processor_id();
 
@@ -219,7 +219,7 @@ static inline void play_dead(void)
 	BUG();
 }
 #else
-static inline void play_dead(void)
+static inline void __noreturn play_dead(void)
 {
 	BUG();
 }