reset: add reset_request()

This is needed in error path to assert previously deasserted
reset by using a saved reset_ctl reference.

Signed-off-by: Patrice Chotard <patrice.chotard@st.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

include/reset.h

@@ -99,6 +99,15 @@ int reset_get_by_index(struct udevice *dev, int index,
 int reset_get_by_name(struct udevice *dev, const char *name,
 		      struct reset_ctl *reset_ctl);
 
+/**
+ * reset_request - Request a reset signal.
+ *
+ * @reset_ctl:	A reset control struct.
+ *
+ * @return 0 if OK, or a negative error code.
+ */
+int reset_request(struct reset_ctl *reset_ctl);
+
 /**
  * reset_free - Free a previously requested reset signal.
  *