ARM: OMAP3: There is no FS USB controller on omap3

We should not select ARCH_OMAP_OTG as the hardware does not
have the legacy FS (Full Speed) USB interface.

Cc: linux-usb@vger.kernel.org
Cc: Kyungmin Park <kyungmin.park@samsung.com>
Acked-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>