MAINTAINERS: Update Zynq git tree location

The git tree for Zynq moved to Github. Update the MAINTAINERS record to
reflect the change.

Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
1 file changed