Update signature of mbedtls_platform_random_delay

Skip parameter and return value from mbedtls_platform_random_delay
to make it more resistant for FI attacks.
diff --git a/tinycrypt/ecc_dsa.c b/tinycrypt/ecc_dsa.c
index c19c73e..3db8536 100644
--- a/tinycrypt/ecc_dsa.c
+++ b/tinycrypt/ecc_dsa.c
@@ -299,7 +299,7 @@
 	/* Accept only if v == r. */
 	diff = uECC_vli_equal(rx, r);
 	if (diff == 0) {
-	    mbedtls_platform_random_delay( 50 );
+	    mbedtls_platform_random_delay();
 		if (diff == 0) {
 			return UECC_SUCCESS;
 		}