hw: basic support for ODROID XU board (Fix #991)
noux_tool_chain_auto & hw_arndale: adjust timeouts

As hw_arndale is a bit slower than foc_arm and spawn_serial timing
calculation has changed in general, timeouts of noux_tool_chain_auto test
must be adjusted.

fix #996
block: let generic driver API work asynchronously

Fix #990
run: smarter timeouts for spawn_serial

Now the boot timeout is the test timeout divided by the minimum amount of boot
trials. The time that is consumed by boot trials is subtracted from the test
timeout.

fix #994
usb block: use generic block driver API (Fix #966)
fixup for commit 7b49dbf2f3aa0d54ff39ada935edbad8be296386