Don't use multiline comments in enums to silence check-names.sh

The sanity checking script tests/scripts/check-names.sh uses a
simple state machine paired with a sequence of `sed` commands to
extract enumeration constants from the code. This code, however,
doesn't work properly when using multiline comments in enumerations
such as recently done in the constants MBEDTLS_CIPHER_PSA_KEY_XXX.

This commit doesn't attempt to make check-names.sh more robust
but instead uses /* ... */ comment indicators in each comment line,
while silences check-names.sh.

Increasing the robustness of check-names.sh is instead tracked
in #2210.
diff --git a/include/mbedtls/cipher_internal.h b/include/mbedtls/cipher_internal.h
index cecad9a..6687b36 100644
--- a/include/mbedtls/cipher_internal.h
+++ b/include/mbedtls/cipher_internal.h
@@ -122,16 +122,16 @@
 typedef enum
 {
     MBEDTLS_CIPHER_PSA_KEY_UNSET = 0,
-    MBEDTLS_CIPHER_PSA_KEY_OWNED, /* Used for PSA-based cipher contexts
-                                   * which use raw key material internally
-                                   * imported into a freshly allocated key slot,
-                                   * and which hence need to destroy that key
-                                   * slot when they are no longer needed. */
-    MBEDTLS_CIPHER_PSA_KEY_NOT_OWNED, /* Used for PSA-based cipher contexts
-                                       * which use a key from a key slot
-                                       * provided by the user, and which hence
-                                       * should not be destroyed when the
-                                       * context is no longer needed. */
+    MBEDTLS_CIPHER_PSA_KEY_OWNED, /* Used for PSA-based cipher contexts which */
+                                  /* use raw key material internally imported */
+                                  /* into a allocated key slot, and which     */
+                                  /* hence need to destroy that key slot      */
+                                  /* when they are no longer needed.          */
+    MBEDTLS_CIPHER_PSA_KEY_NOT_OWNED, /* Used for PSA-based cipher contexts   */
+                                      /* which use a key from a key slot      */
+                                      /* provided by the user, and which      */
+                                      /* hence should not be destroyed when   */
+                                      /* the context is no longer needed.     */
 } mbedtls_cipher_psa_key_ownership;
 
 typedef struct