ta: pkcs11: fix build warning on unused arguments

Add missing __maybe_unused attribute for function arguments not
used when the pkcs11 TA is built with NDEBUG directive, as shown
by the following build trace message:

ta/pkcs11/src/pkcs11_attributes.c: In function ‘get_default_value’:
ta/pkcs11/src/pkcs11_attributes.c:261:61: warning: unused parameter ‘id’ [-Wunused-parameter]
  261 | static enum pkcs11_rc get_default_value(enum pkcs11_attr_id id, void **value,
      |                                         ~~~~~~~~~~~~~~~~~~~~^~
ta/pkcs11/src/pkcs11_attributes.c: In function ‘check_created_attrs_against_processing’:
ta/pkcs11/src/pkcs11_attributes.c:1647:73: warning: unused parameter ‘head’ [-Wunused-parameter]
 1647 |                                                       struct obj_attrs *head)
      |                                                       ~~~~~~~~~~~~~~~~~~^~~~

Fixes: 63f89ca ("ta: pkcs11: attribute helper functions")
Reviewed-by: Jerome Forissier <jerome.forissier@linaro.org>
Signed-off-by: Etienne Carriere <etienne.carriere@foss.st.com>

Author: etienne-lms

ta/pkcs11/src/pkcs11_attributes.c

@@ -258,8 +258,8 @@ static enum pkcs11_rc set_mandatory_attributes(struct obj_attrs **out,
 	return rc;
 }
 
-static enum pkcs11_rc get_default_value(enum pkcs11_attr_id id, void **value,
-					uint32_t *size)
+static enum pkcs11_rc get_default_value(enum pkcs11_attr_id id __maybe_unused,
+					void **value, uint32_t *size)
 {
 	/* should have been taken care of already */
 	assert(!pkcs11_attr_is_boolean(id));
@@ -1643,8 +1643,9 @@ static bool __maybe_unused check_attr_bval(uint32_t proc_id __maybe_unused,
  * @proc_id - PKCS11_CKM_xxx
  * @head - head of the attributes of the to-be-created object.
  */
-enum pkcs11_rc check_created_attrs_against_processing(uint32_t proc_id,
-						      struct obj_attrs *head)
+enum pkcs11_rc
+check_created_attrs_against_processing(uint32_t proc_id,
+				       struct obj_attrs *head __maybe_unused)
 {
 	/*
 	 * Processings that do not create secrets are not expected to call