style(expect): normalize debugging messages

A minor style cleanup to the messages printed by the Expect scripts to
make them a bit more consistent and descriptive.

Signed-off-by: Chris Kay <chris.kay@arm.com>
Change-Id: Ibd8ccb4423bd5aaeffc99c2f3602123794dc6200
(cherry picked from commit 78ea2c38582da41eb8f9509a2130e702cdf0f1c9)
diff --git a/expect/busybox.inc b/expect/busybox.inc
index a7f781d..8110bc8 100644
--- a/expect/busybox.inc
+++ b/expect/busybox.inc
@@ -8,6 +8,6 @@
 # This script is not standalone and should be sourced by a top expect script.
 #
 
-expect_string "init.sh" "Init"
-expect_re ".* # " "TEST SUCCESS"
+expect_string "init.sh" "Linux is booting"
+expect_re ".* # " "Linux reached the root prompt"
 exit_uart 0