[ftools] flpgbti2c: added option -L, to select I2C register address byte order
I2C register address byte order (for 2-byte addresses), for example: lpGBT has LSB first, ALTIROC2 has MSB first
I2C register address byte order (for 2-byte addresses), for example: lpGBT has LSB first, ALTIROC2 has MSB first