Input: add Zhen Hua driver

Input: add Zhen Hua driver

This is a driver for Zhen Hua PPM-4CH RC transmitter (commonly used in cheap
Ready To Fly RC helicopters by Walkera) which using "Zhen Hua 5-byte protocol"
for using them as a four axis joystick via serial port.  Transmitter connected
to serial port (19200 8N1) sending periodically 5 bytes where first byte is for
synchronization and next four bytes are values of axis.

Signed-off-by: Martin Kebert <gkmarty@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>