doc/secvar: Fix table markup

Where the table grid intersect there needs to be a '+' rather than a '|'

Signed-off-by: Oliver O'Halloran <oohall@gmail.com>

doc/device-tree/ibm,opal/secvar/binding.rst

@@ -155,19 +155,19 @@ for more detail.
 
 +-----------------+-----------------------------------------------+
 | update-status   | Generic Reason                                |
-+-----------------|-----------------------------------------------+
++-----------------+-----------------------------------------------+
 | OPAL_SUCCESS    | Updates were found and processed successfully |
-+-----------------|-----------------------------------------------+
++-----------------+-----------------------------------------------+
 | OPAL_EMPTY      | No updates were found, none processed         |
-+-----------------|-----------------------------------------------+
++-----------------+-----------------------------------------------+
 | OPAL_PARAMETER  | Malformed, or unexpected update data blob     |
-+-----------------|-----------------------------------------------+
++-----------------+-----------------------------------------------+
 | OPAL_PERMISSION | Update failed to apply, possible auth failure |
-+-----------------|-----------------------------------------------+
++-----------------+-----------------------------------------------+
 | OPAL_HARDWARE   | Misc. storage-related error                   |
-+-----------------|-----------------------------------------------+
++-----------------+-----------------------------------------------+
 | OPAL_RESOURCE   | Out of space (reported by storage             |
-+-----------------|-----------------------------------------------+
++-----------------+-----------------------------------------------+
 | OPAL_NO_MEM     | Out of memory                                 |
 +-----------------+-----------------------------------------------+