Commit 38225f2e ("ARM/omap1: switch to use dma_direct_set_offset for
lbus DMA offsets") removed a lot of mach/memory.h, but left the USB
offset handling split into arch/arm/mach-omap1/usb.c and
drivers/usb/host/ohci-omap.c.

This can cause a randconfig build warning that now fails the build
with -Werror:

arch/arm/mach-omap1/usb.c:561:30: error: 'omap_1510_usb_ohci_nb' defined but not used [-Werror=unused-variable]
  561 | static struct notifier_block omap_1510_usb_ohci_nb = {
      |                              ^~~~~~~~~~~~~~~~~~~~~

Move it all into the platform file to get rid of the final
location that relies on mach/memory.h.
Acked-by: NFelipe Balbi <felipe.balbi@linux.intel.com>
Acked-by: NAlan Stern <stern@rowland.harvard.edu>
Acked-by: NTony Lindgren <tony@atomide.com>
Acked-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20210927144118.2464881-1-arnd@kernel.org'
Signed-off-by: NArnd Bergmann <arnd@arndb.de>