usb: ulpi: rename operations {read|write}_dev to simply {read|write}

With the removal of the old {read|write} operations, we can now safely
rename the new api operations {read|write}_dev to use the shorter and
clearer names {read|write}, respectively.

Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Tal Shorer <tal.shorer@gmail.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>