Introduce new USB driver for Synopsys DesignWare USB OTG core.

Based on g#844 and g#949, it is intended as a replacement for the
current s3c6400x USB driver.

The DesignWare USB OTG core is integrated into many SoC's, however
HW core version and capabilities (mainly DMA mode, Tx FIFO mode,
FIFO size and number of available IN/OUT endpoins) may differ:

CPU       targets        HW ver  DMA  NPTX FIFO  FIFO sz  #IN/OUT
--------  -------------  ------  ---  ---------  -------  -------
as3525v2  sansaclipplus  2.60a   Yes  Dedicated  0x535    4/4
          sansaclipv2
          sansaclipzip
          sansafuzev2
s5l8701   ipodnano2g     2.20a   Yes  Shared     0x500    4/5
s5l8702   ipod6g         2.60a   Yes  Dedicated  0x820    7/7
          ipodnano3g
s5l8720   ipodnano4g     ?       ?    ?          ?        ?

Functionality supported by this driver:
- Device mode, compatible with USB 1.1/2.0 hosts.
- Shared FIFO (USB_DW_SHARED_FIFO) or dedicated FIFOs.
- No DMA (USB_DW_ARCH_SLAVE) or internal DMA mode.
- Concurrent transfers: control, bulk (usb_storage, usb_serial) and
  interrupt (usb_hid).

Actually this driver is not used by any CPU, it will be enabled for
each individual CPU/target in next patches.

Change-Id: I74a1e836d18927a31f6977d71115fb442477dd5f

firmware/usbstack/usb_serial.c

@@ -19,6 +19,7 @@
  *
  ****************************************************************************/
 #include "string.h"
+#include "config.h"
 #include "system.h"
 #include "usb_core.h"
 #include "usb_drv.h"
@@ -60,6 +61,11 @@ static unsigned char send_buffer[BUFFER_SIZE]
     USB_DEVBSS_ATTR __attribute__((aligned(32)));
 static unsigned char receive_buffer[32]
     USB_DEVBSS_ATTR __attribute__((aligned(32)));
+#if CONFIG_USBOTG == USBOTG_DESIGNWARE
+/* Aligned transit buffer */
+static unsigned char transit_buffer[32]
+    USB_DEVBSS_ATTR __attribute__((aligned(4)));
+#endif
 
 static void sendout(void);
 
@@ -163,8 +169,13 @@ static void sendout(void)
     if(buffer_transitlength > 0)
     {
         buffer_length -= buffer_transitlength;
+#if CONFIG_USBOTG == USBOTG_DESIGNWARE
+        memcpy(transit_buffer,&send_buffer[buffer_start],buffer_transitlength);
+        usb_drv_send_nonblocking(ep_in,transit_buffer,buffer_transitlength);
+#else
         usb_drv_send_nonblocking(ep_in, &send_buffer[buffer_start],
                 buffer_transitlength);
+#endif
     }
 }