[IA64] Include Kconfig.preempt

arch/ia64/Kconfig failed to include kernel/Kconfig.preempt that meant it
did not support PREEMPT_VOLUNTARY and PREEMPT_BKL (inadvertently).
This was recently noticed when the newly-added PREEMPT_NOTIFIERS in
Kconfig.preempt that was "select"ed from drivers/kvm/Kconfig (therefore)
started giving bogus warnings ('select' used by config symbol 'KVM' refers
to undefined symbol 'PREEMPT_NOTIFIERS') on ia64 builds.

So let's remove the open-coded definition of CONFIG_PREEMPT in
arch/ia64/Kconfig and replace it with just including Kconfig.preempt
instead, like the other archs do.

Signed-off-by: Satyam Sharma <satyam@infradead.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>

arch/ia64/Kconfig

@@ -327,17 +327,7 @@ config FORCE_CPEI_RETARGET
 	This option it useful to enable this feature on older BIOS's as well.
 	You can also enable this by using boot command line option force_cpei=1.
 
-config PREEMPT
-	bool "Preemptible Kernel"
-        help
-          This option reduces the latency of the kernel when reacting to
-          real-time or interactive events by allowing a low priority process to
-          be preempted even if it is in kernel mode executing a system call.
-          This allows applications to run more reliably even when the system is
-          under load.
-
-          Say Y here if you are building a kernel for a desktop, embedded
-          or real-time system.  Say N if you are unsure.
+source "kernel/Kconfig.preempt"
 
 source "mm/Kconfig"