INIT_THREAD enables interrupts in the thread_struct's saved flags.  This
means that interrupts get enabled in the middle of context_switch()
while switching to new tasks that get forked off the init task during
boot.  Don't do this.

Fixes the following splat on boot with spinlock debugging on:

  BUG: spinlock cpu recursion on CPU#0, swapper/2
   lock: runqueues+0x0/0x47c, .magic: dead4ead, .owner: swapper/0,
  .owner_cpu: 0
  CPU: 0 PID: 2 Comm: swapper Not tainted 3.19.0-08796-ga747b55 #285

  Call Trace:
  [<c0032b80>] spin_bug+0x2a/0x36
  [<c0032c98>] do_raw_spin_lock+0xa2/0x126
  [<c01964b0>] _raw_spin_lock+0x20/0x2a
  [<c00286c8>] scheduler_tick+0x22/0x76
  [<c003db2c>] update_process_times+0x5e/0x72
  [<c0007a94>] timer_interrupt+0x4e/0x6a
  [<c00378d6>] handle_irq_event_percpu+0x54/0xf2
  [<c00379c4>] handle_irq_event+0x50/0x74
  [<c003988e>] handle_simple_irq+0x6c/0xbe
  [<c0037270>] generic_handle_irq+0x2a/0x36
  [<c0004c40>] do_IRQ+0x38/0x84
  [<c000662e>] crisv32_do_IRQ+0x54/0x60
  [<c0006204>] IRQ0x4b_interrupt+0x34/0x3c
  [<c0192baa>] __schedule+0x24a/0x532
  [<c00056b4>] ret_from_kernel_thread+0x0/0x14
Signed-off-by: Rabin Vincent <rabin@rab.in>
Signed-off-by: Jesper Nilsson <jespern@axis.com>