By not forcing a fixed oversampling rate we can achieve better baud rate
accuracy than otherwise possible.
For example, when requesting 115200 with a module clock of 4 MHz,
picking an oversampling rate of 17 (instead of hardware
default 16) yields 117647 baud instead of 125000 baud as the best
matching rate. Better matching baud rate between receiver and
transmitter results in a lower probability of transmission errors.
