[IA64] Drop duplicated "config IOMMU_HELPER"

One entry for this in arch/ia64/Kconfig should be enough.

Reported-by: Christoph Egger <siccegge@cs.fau.de>
Signed-off-by: Tony Luck <tony.luck@intel.com>
diff --git a/arch/ia64/Kconfig b/arch/ia64/Kconfig
index 4d4f418..9676100 100644
--- a/arch/ia64/Kconfig
+++ b/arch/ia64/Kconfig
@@ -59,9 +59,6 @@
 config SWIOTLB
        bool
 
-config IOMMU_HELPER
-       bool
-
 config GENERIC_LOCKBREAK
 	def_bool n