ARM: pxa: stargate2: use device properties for at24 eeprom

We want to work towards phasing out the at24_platform_data structure.
There are few users and its contents can be represented using generic
device properties. Using device properties only will allow us to
significantly simplify the at24 configuration code.

Remove the at24_platform_data structure and replace it with an array
of property entries. Drop the byte_len/size property, as the model name
already implies the EEPROM's size.

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
Acked-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>