arm64: zynqmp: Disable WP on zcu111

On this board there is SD slot without WP connected.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Link: https://lore.kernel.org/r/88e41d4f5c6a7353762bd5ad38b92ce352c3a123.1623684253.git.michal.simek@xilinx.com