Fix: `ip` context is expressed as a base-10 field

Fix: `ip` context is expressed as a base-10 field

The base for UST context field `ip` was changed from 16 (hexadecimal) to
10 (decimal), most likely an unintentional copy&paste error in 4e48b5d.

Base 16 is more common for addresses, hence this change should probably
be reverted.

Reported-by: Thomas Gatterweh <thomas.gatterweh@siemens.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: Ibb28a4768e99e1089577babf2fd74476ae367a89