docs: ia64: Fix a typo ("identify mappings")

The correct term here, also used in the next line, is "identity
mappings". "itentify mappings" was probably just a typo.

Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Link: https://lore.kernel.org/r/20221101160609.961950-1-j.neuschaefer@gmx.net


Signed-off-by: Jonathan Corbet <corbet@lwn.net>