ARM: zynq: Convert at25 binding to new description on zc770-xm013

The commit f8f79fa6 ("dt-bindings: at25: convert the binding document
to yaml") converted binding to yaml and 3 deprecated properties pop up.

The patch is fixing these warnings:
.../zynq-zc770-xm013.dt.yaml: eeprom@2: 'pagesize' is a required property
.../zynq-zc770-xm013.dt.yaml: eeprom@2: 'size' is a required property
.../zynq-zc770-xm013.dt.yaml: eeprom@2: 'address-width' is a required property
>From schema: .../Documentation/devicetree/bindings/eeprom/at25.yaml

by converting them to new binding.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Link: https://lore.kernel.org/r/be2c1125d98386033e182012eb08986924707a76.1606397101.git.michal.simek@xilinx.com