Returns the current state of modem control inputs. The state
of the outputs should not be returned, since the core keeps
track of their state. The state information should include:
- - TIOCM_DCD state of DCD signal
+ - TIOCM_CAR state of DCD signal
- TIOCM_CTS state of CTS signal
- TIOCM_DSR state of DSR signal
- TIOCM_RI state of RI signal