The USB_OMAP3 driver was (re)added in commit e74e9f620a6 as part
of migrating to DM_USB but the config already had MUSB_OMAP2PLUS
which is the newer musb driver and what other omap3 devices use.
So drop it so we can drop the old driver.
Signed-off-by: Peter Robinson <pbrobinson@gmail.com>