USB: Fix s3c2410_udc usb speed handling

The new composite framework revealed a weakness in the
s3c2410_udc driver gadget register function. Instead of
checking if speed asked for was USB_LOW_SPEED upon
usb_gadget_register() to deny service, it checked only
for USB_FULL_SPEED, thus denying service to usb high
speed capable gadgets (like g_ether).

Signed-off-by: Yauhen Kharuzhy <jekhor@gmail.com>
Cc: stable <stable@kernel.org>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>