changes for example code for AT24C512_Demo

[shirish47]

this code works on AT24C512, but when we provide EEPROM address more than 255 it does not work. Type casting for most significant Byte causes that problem,
Wire.beginTransmission(DEV_ADDR); Wire.write((uint8_t)addr>>8); Wire.write((uint8_t)addr); Wire.write(pbuf, len);

code below works fine.

Wire.beginTransmission(DEV_ADDR); Wire.write((uint8_t) (addr>>8) ); Wire.write((uint8_t)addr); Wire.write(pbuf, len);

putting addr>>8 in bracket.