dt-bindings: firmware: Remove xlnx,zynqmp-firmware.txt file

The funtionality of xlnx,zynqmp-firmware.txt is replaced with
xlnx,zynqmp-firmware.yaml bindings so this patch removes the
zynqmp-firmware.txt file

Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Nava kishore Manne <nava.manne@xilinx.com>
Link: https://lore.kernel.org/r/20210626155248.5004-5-nava.manne@xilinx.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>