ecp: revert changes to ECP module and test suite

Signed-off-by: Valerio Setti <valerio.setti@nordicsemi.no>
diff --git a/library/ecp.c b/library/ecp.c
index a794b3b..08fbe86 100644
--- a/library/ecp.c
+++ b/library/ecp.c
@@ -3316,7 +3316,7 @@
     return ret;
 }
 
-#if !defined(MBEDTLS_USE_PSA_CRYPTO)
+
 /*
  * Check a public-private key pair
  */
@@ -3357,7 +3357,6 @@
 
     return ret;
 }
-#endif /* !MBEDTLS_USE_PSA_CRYPTO */
 
 /*
  * Export generic key-pair parameters.