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>
diff --git a/programs/psa/aead_demo.c b/programs/psa/aead_demo.c
index 5bc0af0..c4ed0dd 100644
--- a/programs/psa/aead_demo.c
+++ b/programs/psa/aead_demo.c
@@ -156,7 +156,7 @@
         return( PSA_ERROR_INVALID_ARGUMENT );
     }
 
-    /* Prepare key attibutes */
+    /* Prepare key attributes */
     psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
     psa_set_key_usage_flags( &attributes, PSA_KEY_USAGE_ENCRYPT );
     psa_set_key_algorithm( &attributes, *alg );