kirkwood: USB OTG support

[Jason S. McMullan]

The following patch leverages the Freescale USB OTG driver
to provide support for the Kirkwood. Both SoCs use the
ARC International USB OTG core IP.

diffstat:
 arch/arm/mach-kirkwood/common.c |   34 +++++++++++++++++++++++++++++-----
 arch/arm/mach-kirkwood/common.h |    1 +
 drivers/usb/gadget/Kconfig      |    2 +-
 3 files changed, 31 insertions(+), 6 deletions(-)