dm: gpio: Rename set_dir_flags() method to update_flags()

The current method is a misnomer since it is also used (e.g. by stm32) to
update pull settings and open source/open drain.

Rename it and expand the documentation to cover a few more details.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Pratyush Yadav <p.yadav@ti.com>

Reviewed-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
diff --git a/test/dm/gpio.c b/test/dm/gpio.c
index d7b85e7..36bbaed 100644
--- a/test/dm/gpio.c
+++ b/test/dm/gpio.c
@@ -81,12 +81,12 @@
 	/* Make it an open drain output, and reset it */
 	ut_asserteq(GPIOD_IS_OUT | GPIOD_IS_OUT_ACTIVE,
 		    sandbox_gpio_get_dir_flags(dev, offset));
-	ut_assertok(ops->set_dir_flags(dev, offset,
-				       GPIOD_IS_OUT | GPIOD_OPEN_DRAIN));
+	ut_assertok(ops->set_flags(dev, offset,
+				   GPIOD_IS_OUT | GPIOD_OPEN_DRAIN));
 	ut_asserteq(GPIOD_IS_OUT | GPIOD_OPEN_DRAIN,
 		    sandbox_gpio_get_dir_flags(dev, offset));
-	ut_assertok(ops->set_dir_flags(dev, offset,
-				       GPIOD_IS_OUT | GPIOD_IS_OUT_ACTIVE));
+	ut_assertok(ops->set_flags(dev, offset,
+				   GPIOD_IS_OUT | GPIOD_IS_OUT_ACTIVE));
 	ut_asserteq(GPIOD_IS_OUT | GPIOD_IS_OUT_ACTIVE,
 		    sandbox_gpio_get_dir_flags(dev, offset));