OP-TEE: Fix typo

Fix double "the" in the OP-TEE document.

Signed-off-by: Martyn Welch <martyn.welch@collabora.com>

content/concepts/op-tee.md

@@ -121,7 +121,7 @@ This works in conjunction with support from the hypervisor to provide memory
 mapping and to provide enumeration of the VMs so that the right context is used
 for each VM. The functionality added to the hypervisor is called the "TEE
 mediator". The advantage of this approach is that, whilst it requires changes
-the the TEE and hypervisor, it keeps the API as seen by the guest OS and
+the TEE and hypervisor, it keeps the API as seen by the guest OS and
 trusted applications the same, and thus existing applications and TAs do not
 need to be made aware of the virtualization used on the platform.