riscv: remove redundant #ifdef check in cpu-hotplug

The cpu-hotplug.c only is built when CONFIG_HOTPLUG_CPU is defined,
it is not needed to check HOTPLUG_CPU in this file.

Signed-off-by: Hui Wang <hui.wang@canonical.com>
Link: https://patch.msgid.link/20260304033403.238012-2-hui.wang@canonical.com
[pjw@kernel.org: removed extra whitespace at EOF]
Signed-off-by: Paul Walmsley <pjw@kernel.org>

arch/riscv/kernel/cpu-hotplug.c

@@ -43,7 +43,6 @@ int __cpu_disable(void)
 	return 0;
 }
 
-#ifdef CONFIG_HOTPLUG_CPU
 /*
  * Called on the thread which is asking for a CPU to be shutdown, if the
  * CPU reported dead to the hotplug core.
@@ -75,4 +74,3 @@ void __noreturn arch_cpu_idle_dead(void)
 	/* It should never reach here */
 	BUG();
 }
-#endif