ARM: dts: lpc3250-phy3250: replace deprecated at25 properties with new ones

ARM: dts: lpc3250-phy3250: replace deprecated at25 properties with new ones

Replace deprecated at25 properties with the required properties (size,
address-width and pagesize), which duplicate the removed properties.

Fix below CHECK_DTB warning:
  arch/arm/boot/dts/nxp/lpc/lpc3250-phy3250.dtb: at25@0 (atmel,at25): 'pagesize' is a required property
  arch/arm/boot/dts/nxp/lpc/lpc3250-phy3250.dtb: at25@0 (atmel,at25): $nodename: 'anyOf' conditional failed, one must be fixed:

Signed-off-by: Frank Li <Frank.Li@nxp.com>
[vzapolskiy: squashed two changes from the series and updated commit message]
Signed-off-by: Vladimir Zapolskiy <vz@mleia.com>