[util] Disable automatic CR->LF conversion in serial-console utility

DUET (the EFI test environment) seems not to handle LF, so inhibit the
CR->LF conversion that the pty does for us by default.  This doesn't
affect operation of gPXE, which will happily accept either CR or LF.

contrib/bochs/serial-console

   $restore_termios = POSIX::Termios->new;
   $termios->getattr ( fileno(STDIN) );
   $restore_termios->getattr ( fileno(STDIN) );
-  $termios->setlflag ( $termios->getlflag &
-		       ~(ICANON) & ~(ECHO) );
+  $termios->setlflag ( $termios->getlflag & ~(ICANON) & ~(ECHO) );
+  $termios->setiflag ( $termios->getiflag & ~(ICRNL) );
   $termios->setattr ( fileno(STDIN), TCSANOW );
 }