USB: at91_udc, misc fixes

This is an update to the AT91 USB Device (Gadget) driver.

Adds support for the Atmel AT91SAM9260 and AT91SAM9261 processors.  The
only difference is how they handle the pullup pin.
[Patch from Patrice Vilchez]

Need to clear any pending USB Device interrupts before registering the
interrupt handler.  The bootloader might have been using the USB Device
port.   [Patch from Peer Georgi]

VBUS detection is handled by a GPIO interrupt which only triggers on a
change. Is is therefore necessary to read the current VBUS state
explicitly at startup.  [Patch from Peer Georgi]

Signed-off-by: Andrew Victor <andrew@sanpeople.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>