test/py: put "Starting U-Boot" into separate log section

The initial boot of U-Boot happens within the context of the first test
that needs to access the U-Boot console when there is no existing
connection. This keeps all activity nestled within test execution, which
fits well into the pytest model. However, this mingles the U-Boot startup
logs with the execution of some test(s), which hides find the boundary
between the two.

To solve this, wrap the "Starting U-Boot" logic into a separate log
section. If the user wishes, they can simply collapse this log section
when viewing the HTML log, to concentrate purely on the test's own
interaction.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Acked-by: Simon Glass <sjg@chromium.org>
diff --git a/test/py/u_boot_console_base.py b/test/py/u_boot_console_base.py
index 5857570..bc2bd76 100644
--- a/test/py/u_boot_console_base.py
+++ b/test/py/u_boot_console_base.py
@@ -293,8 +293,8 @@
         if self.p:
             return
         try:
+            self.log.start_section('Starting U-Boot')
             self.at_prompt = False
-            self.log.action('Starting U-Boot')
             self.p = self.get_spawn()
             # Real targets can take a long time to scroll large amounts of
             # text if LCD is enabled. This value may need tweaking in the
@@ -329,6 +329,8 @@
             self.log.error(str(ex))
             self.cleanup_spawn()
             raise
+        finally:
+            self.log.end_section('Starting U-Boot')
 
     def cleanup_spawn(self):
         """Shut down all interaction with the U-Boot instance.