sparc: Use generic init_task

Same code. Use the generic version.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: "David S. Miller" <davem@davemloft.net>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Link: http://lkml.kernel.org/r/20120503085035.463573011@linutronix.de