psa_crypto_ecp: fix comment for secp224k1 in check_ecc_parameters

Signed-off-by: Valerio Setti <valerio.setti@nordicsemi.no>
diff --git a/library/psa_crypto_ecp.c b/library/psa_crypto_ecp.c
index d6b640c..4d9a59b 100644
--- a/library/psa_crypto_ecp.c
+++ b/library/psa_crypto_ecp.c
@@ -80,8 +80,8 @@
                 case 256:
                     return PSA_SUCCESS;
                 /* secp224k1 is not and will not be supported in PSA (#3541).
-                 * Note: secp224k1 has 225-bit private keys which are rounded
-                 * up to 232 for their representation. */
+                 * Note: secp224k1 has 224-bit coordinates but 225-bit private
+                 * keys which are rounded up to 232 for their representation. */
                 case 224:
                 case 232:
                     return PSA_ERROR_NOT_SUPPORTED;