xilinx: Convert xlnx,eeprom property to nvmem alias

Convert all boards to use nvmem alias instead of xlnx,eeprom. The change is
done based on discussion in the link below.

Link: https://lore.kernel.org/r/CAL_JsqLMDqpkyg-Q7mUfw-XH67-v068Q6e9wTq2UOoN=0-_coQ@mail.gmail.com


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