Fix error in the guide to drivers

There is no export_key entry point for transparent drivers.

Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>
diff --git a/docs/psa-driver-example-and-guide.md b/docs/psa-driver-example-and-guide.md
index ff66124..ae3c04c 100644
--- a/docs/psa-driver-example-and-guide.md
+++ b/docs/psa-driver-example-and-guide.md
@@ -29,8 +29,8 @@
 | Transparent Driver  | Opaque Driver       |
 |---------------------|---------------------|
 | `import_key`        | `import_key`        |
-| `export_key`        | `export_key`        |
 | `export_public_key` | `export_public_key` |
+|                     | `export_key`        |
 |                     | `copy_key`          |
 |                     | `get_builtin_key`   |