arm: omap1: get rid of OMAP_TAG_USB

OMAP_TAGS should vanish soon since they're not generic arm tags.
Most of them can be converted to a platform_data or parsed
from a command line like e.g. serial tag.

For OMAP_TAG_USB we just let boards call omap_usb_init()
passing a pointer to omap_usb_config.

This patch is compile tested only.

Signed-off-by: Felipe Balbi <felipe.balbi@nokia.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>