fix/work around dependency issues when !MBEDTLS_ECP_C

Signed-off-by: Tomi Fontanilles <tomi.fontanilles@nordicsemi.no>
diff --git a/library/pk_internal.h b/library/pk_internal.h
index d4b140a..025ee8b 100644
--- a/library/pk_internal.h
+++ b/library/pk_internal.h
@@ -44,7 +44,7 @@
 #define PEM_BEGIN_ENCRYPTED_PRIVATE_KEY_PKCS8 "-----BEGIN ENCRYPTED PRIVATE KEY-----"
 #define PEM_END_ENCRYPTED_PRIVATE_KEY_PKCS8   "-----END ENCRYPTED PRIVATE KEY-----"
 
-#if !defined(MBEDTLS_PK_USE_PSA_EC_DATA)
+#if defined(MBEDTLS_PK_HAVE_ECC_KEYS) && !defined(MBEDTLS_PK_USE_PSA_EC_DATA)
 /**
  * Public function mbedtls_pk_ec() can be used to get direct access to the
  * wrapped ecp_keypair structure pointed to the pk_ctx. However this is not
@@ -80,7 +80,7 @@
             return NULL;
     }
 }
-#endif /* !MBEDTLS_PK_USE_PSA_EC_DATA */
+#endif /* MBEDTLS_PK_HAVE_ECC_KEYS && !MBEDTLS_PK_USE_PSA_EC_DATA */
 
 #if defined(MBEDTLS_PK_HAVE_ECC_KEYS)
 static inline mbedtls_ecp_group_id mbedtls_pk_get_ec_group_id(const mbedtls_pk_context *pk)