um: Use generic init_task

Same code. Use the generic version.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Richard Weinberger <richard@nod.at>
Link: http://lkml.kernel.org/r/20120503085035.592937512@linutronix.de

diff --git a/arch/um/kernel/um_arch.c b/arch/um/kernel/um_arch.c
index ba00eae..4db8770 100644
--- a/arch/um/kernel/um_arch.c
+++ b/arch/um/kernel/um_arch.c
@@ -10,6 +10,7 @@
 #include <linux/seq_file.h>
 #include <linux/string.h>
 #include <linux/utsname.h>
+#include <linux/sched.h>
 #include <asm/pgtable.h>
 #include <asm/processor.h>
 #include <asm/setup.h>
@@ -47,6 +48,10 @@
 	.ipi_pipe		= { -1, -1 }
 };
 
+union thread_union cpu0_irqstack
+	__attribute__((__section__(".data..init_irqstack"))) =
+		{ INIT_THREAD_INFO(init_task) };
+
 unsigned long thread_saved_pc(struct task_struct *task)
 {
 	/* FIXME: Need to look up userspace_pid by cpu */