stdout-flush-wrapper.sh: Increase sleep time to 5s

As there're still cases of race condition with LAVA's reading of output.

Signed-off-by: Paul Sokolovsky <paul.sokolovsky@linaro.org>
Change-Id: I5f88a09b2a6e1885713f01195811d4d07a7ca80b
diff --git a/stdout-flush-wrapper.sh b/stdout-flush-wrapper.sh
index c164d29..9729cf8 100755
--- a/stdout-flush-wrapper.sh
+++ b/stdout-flush-wrapper.sh
@@ -9,4 +9,4 @@
 cmd="$1"
 shift
 stdbuf -oL "$cmd" "$@"
-sleep 3
+sleep 5