CONFIG_ITANIUM is not available for thedefaultarchitecture x86.
Result is shown for architecture ia64
default or selected kernelversion does not have config value CONFIG_ITANIUM.
Result is shown for kernelversion 6.9.9

Itanium

configname: CONFIG_ITANIUM

Processor type
└─>Itanium
In linux kernel since version 2.6.12  
Select your IA-64 processor type. The default is Itanium.
This choice is safe for all IA-64 systems, but may not perform
optimally on systems with, say, Itanium 2 or newer processors.