Several of the USB timeouts were chosen on the principle of "pick an
arbitrary but ridiculously large value, just to be safe".  It turns
out that some of the timeouts permitted by the USB specification are
even larger: for example, control transactions are allowed to take up
to five seconds to complete.

Fix up these USB timeout values to match those found in the USB2
specification.

Debugged-by: Robin Smidsrød <robin@smidsrod.no>
Tested-by: Robin Smidsrød <robin@smidsrod.no>
Signed-off-by: Michael Brown <mcb30@ipxe.org>