Added support to get/set flow control line levels using TIOCMGET and
TIOCMSET.
Added support for RTSCTS hardware flow control.
cp2101_get_config and cp2101_set_config modified to support long request
strings, required for configuring flow control.

Signed-off-by: Craig Shelley <craig@microtron.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>