ARM64: zynqmp: Remove netdev.h from board file

ARM64: zynqmp: Remove netdev.h from board file

Including netdev.h is causing compilation warning:
+ int fecmxc_register_mii_postcall(struct eth_device *dev, int
(*cb)(int));
+                                         ^
w+In file included from ../board/xilinx/zynqmp/zynqmp.c:9:0:
w+../include/netdev.h:204:41: warning: ‘struct eth_device’ declared
inside parameter list [enabled by default]
w+../include/netdev.h:204:41: warning: its scope is only this definition
or declaration, which is probably not what you want [enabled by default]

This patch removes it.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>