usb: ohci: Add header file for ARCH_DMA_MINALIGN

This is defined in the asm/cache.h header file. Update this header file to
include it so it gets the same value consistently across U-Boot.

This fixes 'usb host' on omapl138_lcdk.

Fixes: 90526e9f ("common: Drop net.h from common header")
Reported-by: Adam Ford <aford173@gmail.com>
Signed-off-by: Simon Glass <sjg@chromium.org>
Tested-by: Adam Ford <aford173@gmail.com>
Reviewed-by: Tom Rini <trini@konsulko.com>