usb: introduce usb_endpointReadTimeout() and usb_endpointWriteTimeout()

usb: introduce usb_endpointReadTimeout() and usb_endpointWriteTimeout()

Allow to specify a timeout for the usb read/write functions. The timeout
is an upper bound on the amount of time (in ms) elapsed before returns.

If timeout is zero, the the function returns immediatly and it basically
works in non-blocking fashion. A negative value for the timeout means
that the function can block indefinitely.

The last case is basically the old usb_endpointRead/Write() behaviour,
so the compatibility with the old API is respected using this value for
the timeout.

git-svn-id: https://src.develer.com/svnoss/bertos/trunk@4772 38d2e660-2303-0410-9eaa-f027e97ec537