USB: partial USB embedded host support

This provides better support for USB "Embedded Host" functionality, which
is a subset of the USB OTG options:

 * External hub support can be disabled;

 * USB peripherals not whitelisted in "otg_whitelist.h" will be rejected
   during enumeration.

These options can allow some savings in software and support.

Signed-off-by: Robin Getz <rgetz@blackfin.uclinux.org>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>