kpatch-test: Fix type error

Shellcheck reports the following error:
SC2145: Argument mixes string and array.

Lets pretend that types are a thing in bash and use the list of
arguments as a single string instead of the array of arguments.

Signed-off-by: Julien Thierry <jthierry@redhat.com>

test/integration/kpatch-test

@@ -108,7 +108,7 @@ else
 fi
 
 error() {
-	echo "ERROR: $@" |tee -a $LOG >&2
+	echo "ERROR: $*" |tee -a $LOG >&2
 	ERROR=$((ERROR + 1))
 }