usb: mv_udc: Improve allocation of qTD items

Allocate the qTD items all at once instead of allocating them
separately. Moreover, make sure each qTD is properly aligned
to 32-bytes boundary and that cache can be safely flushed over
each qTD touple.

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>

include/usb/mv_udc.h

@@ -77,6 +77,7 @@ struct mv_drv {
 	struct ehci_ctrl		*ctrl;
 	struct ept_queue_head		*epts;
 	struct ept_queue_item		*items[2 * NUM_ENDPOINTS];
+	uint8_t				*items_mem;
 	struct mv_ep			ep[NUM_ENDPOINTS];
 };