libpayload: usb: Make OHCI work with ARM systems

This patch enables the OHCI driver to use DMA memory, which is necessary
for ARM systems where DMA devices are not cache coherent. I really only
need this to test some later OHCI changes, but it was easy enough...
copied almost verbatim from ehci.c.

Change-Id: Ia717eef28340bd6182a6782e83bfdd0693cf0db1
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/193730
Reviewed-by: Stefan Reinauer <reinauer@chromium.org>
(cherry picked from commit e46b6ebc439e86a00e13bf656d60cf6c186a3777)
Signed-off-by: Isaac Christensen <isaac.christensen@se-eng.com>
Reviewed-on: http://review.coreboot.org/7010
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

payloads/libpayload/drivers/usb/ohci_private.h

@@ -257,6 +257,8 @@
 		hcca_t *hcca;
 		usbdev_t *roothub;
 		ed_t *periodic_ed;
+#define DMA_SIZE (64 * 1024)
+		void *dma_buffer;
 	} ohci_t;
 
 	typedef enum { OHCI_SETUP=0, OHCI_OUT=1, OHCI_IN=2, OHCI_FROM_TD=3 } ohci_pid_t;