pk/pk_wrap: replace ECDSA_C with generic ECDSA capabilities' defines

Signed-off-by: Valerio Setti <valerio.setti@nordicsemi.no>
diff --git a/library/pk.c b/library/pk.c
index b01694c..4efe479 100644
--- a/library/pk.c
+++ b/library/pk.c
@@ -114,7 +114,7 @@
         case MBEDTLS_PK_ECKEY_DH:
             return &mbedtls_eckeydh_info;
 #endif
-#if defined(MBEDTLS_ECDSA_C)
+#if defined(MBEDTLS_PK_CAN_ECDSA_SIGN) || defined(MBEDTLS_PK_CAN_ECDSA_VERIFY)
         case MBEDTLS_PK_ECDSA:
             return &mbedtls_ecdsa_info;
 #endif