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
diff --git a/expect/spm-linux-uart0.exp b/expect/spm-linux-uart0.exp
index 1895bd8..beec5c1 100644
--- a/expect/spm-linux-uart0.exp
+++ b/expect/spm-linux-uart0.exp
@@ -8,7 +8,7 @@
 
 expect {
 	"Please press Enter to activate this console." {
-		puts "<<Linux PVM booted>>"
+		message "Linux PVM booted"
 		send "\r"
 	}
 }
@@ -21,7 +21,7 @@
 
 expect {
 	"Hafnium successfully loaded with 1 VMs:" {
-		puts "<<Hafnium driver started>>"
+		message "Hafnium driver started"
 	}
 }