usb: mv_udc: Clean up the EP initialization

Move the constant values that are programmed into mv_ep.ep into
separate static const structure so they can be memcpy()'d when
the initialization happens.

Moveover, we only every init NUM_ENDPOINTS, not 2 * NUM_ENDPOINTS,
so fix this bug as well.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Fabio Estevam <fabio.estevam@freescale.com>
Cc: Lei Wen <leiwen@marvell.com>
Cc: Otavio Salvador <otavio@ossystems.com.br>
Cc: Stefano Babic <sbabic@denx.de>