Fix gamepad axis brake behaviour

- It was actually ACCELERATION axis input that was predominantly broken!
    - It was inexplicably slightly under double what it should be (98 instead of the digital value of 50), which meant brake analog input struggled to dampen it.
    - Analog brake deceleration also gets a slight buff, from 24 to 25 (previously off from the digital value of 25 due to integer division rounding)
- Remove a pointless, always-true condition for brake handling.
    - Checked whether accel was held down OR whether `cmd->forwardmove` was less than or equal 0...
    - But further up the same function, `cmd` was invariably overwritten with a blank `I_BaseTiccmd`!
    - Therefore, `cmd->forwardmove` would always equal 0, and the `forwardmove` subtraction would always occur.