Fix additional misspellings found by codespell

Remaining hits seem to be hex data, certificates,
and other miscellaneous exceptions.
List generated by running codespell -w -L 
keypair,Keypair,KeyPair,keyPair,ciph,nd

Signed-off-by: Andrzej Kurek <andrzej.kurek@arm.com>

scripts/generate_ssl_debug_helpers.py

@@ -289,7 +289,7 @@ class SignatureAlgorithmDefinition:
             {translation_table}
                 }};
 
-                return "UNKOWN";
+                return "UNKNOWN";
             }}''')
         body = body.format(translation_table='\n'.join(translation_table))
         return body