kokoro: hostcheck: Wait 30 seconds at the beginning

The storage device needs a little bit of time to be attached. Wait at the
beginning to make sure the storage device is really not mounted.

Signed-off-by: Daniel Schultz <d.schultz@phytec.de>

.github/kokoro/steps/hostcheck.sh

diff --git a/.github/kokoro/steps/hostcheck.sh b/.github/kokoro/steps/hostcheck.sh
index e2a83ff..3ac4459 100755
--- a/.github/kokoro/steps/hostcheck.sh
+++ b/.github/kokoro/steps/hostcheck.sh
@@ -13,6 +13,8 @@
 echo "========================================"
 echo "Check storage"
 echo "----------------------------------------"
+# Wait 30 seconds to not check the storage too early.
+sleep 30
 set -x +e
 mount | grep /tmpfs
 MOUNT_RET=$?