ehci-hcd.c, musb_core, usb.h: Add USB_DMA_MINALIGN define for cache alignment

The USB spec says that 32 bytes is the minimum required alignment.
However on some platforms we have a larger minimum requirement for cache
coherency.  In those cases, use that value rather than the USB spec
minimum.  We add a cpp check to <usb.h> to define USB_DMA_MINALIGN and
make use of it in ehci-hcd.c and musb_core.h.  We cannot use MAX() here
as we are not allowed to have tests inside of align(...).

Signed-off-by: Tom Rini <trini@ti.com>
[marek.vasut]: introduce some crazy macro voodoo
Signed-off-by: Marek Vasut <marex@denx.de>
[ilya.yanok]: moved external buffer fixes to separate patch,
we use {ALLOC,DEFINE}_ALIGN_BUFFER macros with alignment of USB_DMA_MINALIGN
for qh_list, qh and qtd structures to make sure they are proper aligned
for both controller and cache operations.
Signed-off-by: Ilya Yanok <ilya.yanok@cogentembedded.com>

include/usb.h

@@ -29,6 +29,16 @@
 #include <usb_defs.h>
 #include <usbdescriptors.h>
 
+/*
+ * The EHCI spec says that we must align to at least 32 bytes.  However,
+ * some platforms require larger alignment.
+ */
+#if ARCH_DMA_MINALIGN > 32
+#define USB_DMA_MINALIGN	ARCH_DMA_MINALIGN
+#else
+#define USB_DMA_MINALIGN	32
+#endif
+
 /* Everything is aribtrary */
 #define USB_ALTSETTINGALLOC		4
 #define USB_MAXALTSETTING		128	/* Hard limit */