ARM64: zynqmp: Remove CONFIG_BOOTP_SERVERIP

When the CONFIG_BOOTP_SERVERIP option is set, we ignore all
dhcp values for the tftp server and use our own serverip and
file name instead.

This is usually not what we want and I doubt it's set for a
good reason on ZynqMP. It definitely hurts if we want to support
uEFI PXE boot on it. So just remove the option for now.

Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>