init_task: Replace CONFIG_HAVE_GENERIC_INIT_TASK

Now that all archs except ia64 are converted, replace the config and
let the ia64 select CONFIG_ARCH_INIT_TASK

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20120503085035.867948914@linutronix.de

arch/sparc/Kconfig

@@ -31,7 +31,6 @@ config SPARC
 	select GENERIC_PCI_IOMAP
 	select HAVE_NMI_WATCHDOG if SPARC64
 	select GENERIC_SMP_IDLE_THREAD
-	select HAVE_GENERIC_INIT_TASK
 
 config SPARC32
 	def_bool !64BIT