A USB disk behind a hub may take longer time to respond command.
Prior to the patch, a magic 2000 ms is set. This patch introduces
a python control (USB_CMD_TIMEOUT) for customizing the timeout if
need. The patch also extends the default timeout to 4196 ms.
This patch does not impact booting time when a platform boots with
a good-conditioning usb disk, because the timeout only takes effect
when a disk does not respond to a USB inquiry for a long time.
Verified: Ehl RVP
Signed-off-by: Stanley Chang <stanley.chang@intel.com>
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