doc: Remove duplicate OPAL_ELOG_WRITE label
This was never implemented and it's documented in the "Future calls"
section.
@@ -20,8 +20,6 @@ There are five OPAL calls from host to OPAL on error log:
#define OPAL_ELOG_RESEND 74
#define OPAL_ELOG_SIZE 75
-.. _OPAL_ELOG_WRITE:
-
Note: :ref:`OPAL_ELOG_WRITE` (72) Unused for now, might be supported in the
future.
