omap34usbboot: Fix failed unexpected 2ndstage response

Looks like at least omap3 needs to wait for about a second before
sending 2ndstage over, probably to let some clocks or voltages to
lock properly on the device. Otherwise we can get error
"unexpected 2ndstage response".

The other USB reads and writes can fail too, so let's add some
error checking and prompt to replug the device on those errors.
ANVL: Updated binaries for omap34usbboot

These will retry connecting to the device on errors.