fdtget-runtest.sh: use printf instead of /bin/echo -e

Not all /bin/echo implementations support the -e option. Instead, use
printf, which appears to be more widely available than /bin/echo -e.

See commit eaec1db "fdtget-runtest.sh: Fix failures when /bin/sh isn't
bash" for history.

I have tested this on Ubuntu 10.04 with /bin/sh pointing to both dash
and bash.

Reported-by: Mike Frysinger <vapier@gentoo.org> # and implemented-by
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Acked-by: David Gibson <david@gibson.dropbear.id.au>

tests/fdtget-runtest.sh

@@ -8,7 +8,7 @@ rm -f $LOG $EXPECT
 trap "rm -f $LOG $EXPECT" 0
 
 expect="$1"
-/bin/echo -e $expect >$EXPECT
+printf '%b\n' "$expect" > $EXPECT
 shift
 
 verbose_run_log_check "$LOG" $VALGRIND $DTGET "$@"