ARM: zynq: Add USB lthor download protocol support

updated the zynq config to support the lthor
download protocol.
This lthor functionality helps us to load linux
images on to DDR/MMC and can boot linux using bootm.
In order to load images the user should run lthor
command run "thor_ram" from u-boot prompt and
then send the images from host using lthor utility.

Define g_dnl_bind_fixup for zynq so that correct vendor
and product ids assigned incase of DFU and lthor.

Signed-off-by: Siva Durga Prasad Paladugu <sivadur@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>