Fix warnings

[brano2]

Someone please fix these compiler warnings:

src/utils/io/i2c.cpp: In member function ‘void hyped::utils::io::I2C::read(uint32_t, uint8_t*, uint16_t)’:
src/utils/io/i2c.cpp:94:7: warning: unused variable ‘ret’ [-Wunused-variable]
   int ret = i2c::readHelper(fd_, rx, len);
       ^

src/utils/io/i2c.cpp: In member function ‘void hyped::utils::io::I2C::write(uint32_t, uint8_t*, uint16_t)’:
src/utils/io/i2c.cpp:106:7: warning: unused variable ‘ret’ [-Wunused-variable]
   int ret = i2c::writeHelper(fd_, tx, len);
       ^