Fix typos

Signed-off-by: Tom Cosgrove <tom.cosgrove@arm.com>
diff --git a/library/pkcs7.c b/library/pkcs7.c
index 010d706..d4059d7 100644
--- a/library/pkcs7.c
+++ b/library/pkcs7.c
@@ -354,7 +354,7 @@
         goto out;
     }
 
-    /* Asssume authenticatedAttributes is nonexistent */
+    /* Assume authenticatedAttributes is nonexistent */
     ret = pkcs7_get_digest_algorithm(p, end_signer, &signer->sig_alg_identifier);
     if (ret != 0) {
         goto out;