test: use better naming for the newly introduced test function

Signed-off-by: Valerio Setti <valerio.setti@nordicsemi.no>
diff --git a/tests/suites/test_suite_pkwrite.function b/tests/suites/test_suite_pkwrite.function
index c5668a0..2868462 100644
--- a/tests/suites/test_suite_pkwrite.function
+++ b/tests/suites/test_suite_pkwrite.function
@@ -127,7 +127,7 @@
 /* END_CASE */
 
 /* BEGIN_CASE */
-void pk_write_check_public_key_derivation(char *priv_key_file,
+void pk_write_public_from_private(char *priv_key_file,
                                           char *pub_key_file)
 {
     mbedtls_pk_context priv_key, pub_key;