When restarting U-Boot in lab mode, ensure_spawned() sets the timeout
to TIMEOUT_MS (30 seconds) before calling _wait_for_boot_prompt(). In
lab mode, _wait_for_banner() is skipped, so TIMEOUT_PREPARE_MS is never
restored.
This causes tests that boot into Linux and then restart U-Boot (like
test_distro_script) to fail with a timeout if the board takes more than
30 seconds to reset and boot.
Fix this by setting the timeout to TIMEOUT_PREPARE_MS (3 minutes) at
the start of _wait_for_boot_prompt() when in lab mode.
Co-developed-by: Claude <noreply@anthropic.com>
Signed-off-by: Simon Glass <simon.glass@canonical.com>
652e93b301