linux-imx

Input: synaptics-rmi4 - change a char type to u8

Smatch doesn't like when we use "%02X" to print char types because,
what about if it's a negative?

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>