dm: Tidy up 'dm tree' output when there are many devices

At present the 'Index' column assumes there is only one digit. But on some
devices (e.g. snow) there are a lot of regulators and GPIO banks. Adjust
the output to allow for two digits without messing up the display.

Also capatalise the heading to match.

Fixes: 5197dafc42 (dm: core: Widen the dump tree to show more of the
driver's name.)

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Liviu Dudau <liviu.dudau@foss.arm.com>
diff --git a/test/py/tests/test_bind.py b/test/py/tests/test_bind.py
index dee3fee..917839f 100644
--- a/test/py/tests/test_bind.py
+++ b/test/py/tests/test_bind.py
@@ -13,7 +13,8 @@
 	else:
 		leaf = leaf + '`'
 	leaf = leaf + '-- ' + name
-	line = ' *{:10.10}  [0-9]*  \[ [ +] \]   {:20.20}  {}$'.format(uclass, drv, leaf)
+	line = (' *{:10.10}   [0-9]*  \[ [ +] \]   {:20.20}  {}$'
+	        .format(uclass, drv, leaf))
 	prog = re.compile(line)
 	for l in lines:
 		if prog.match(l):