RTEMS | Add the support for i2c driver in the aarch64/raspberrypi bsp (!363)

[Kinsey Moore (@opticron)]

Kinsey Moore commented on a discussion on bsps/aarch64/raspberrypi/i2c/raspberrypi-i2c.c: https://gitlab.rtems.org/rtems/rtos/rtems/-/merge_requests/363#note_122272

 > +        ++divider;
 > +        clock_rate = BSC_CORE_CLK_HZ / divider;
 > +    }
 > +    
 > +    BCM2835_REG(bus->base_address + BCM2711_I2C_DIV) = divider;
 > +
 > +    bus->input_clock = clock_rate;
 > +
 > +    return 0;
 > +}
 > +
 > +static int rpi_i2c_setup_transfer(raspberrypi_i2c_bus *bus)
 > +{
 > +    int rv;
 > +    while(bus->remaining_transfers > 0){
 > +        bus->remaining_bytes = bus->remaining_transfers > 1 ? 0xFFFF : (bus->current_buffer_size & 0xFFFF);

This could be broken apart and explained with a comment in the code. It seems like there might also be an off-by-one error here. Magic numbers sprinkled in the code are discouraged, so I've :
```
/* I would expect the correct value here to be 0x10000 instead of 0xFFFF */
/* Full transfer size is 0xFFFF bytes */
#define I2C_TRANSFER_SIZE 0xFFFF
bus->remaining_bytes = I2C_TRANSFER_SIZE;
/* If there is only 1 transfer remaining, consume the remainder of the data */
if (bus->remaining_transfers == 1) {
  bus->remaining_bytes = bus->current_buffer_size % I2C_TRANSFER_SIZE;
}
```

-- 
View it on GitLab: https://gitlab.rtems.org/rtems/rtos/rtems/-/merge_requests/363#note_122272
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