Input: edt-ft5x06 - fix access to non-existing register

reg_addr->reg_report_rate is supposed to exist in M06, not M09.

The driver is written to skip avoids access to non-existing registers
when the register address is NO_REGISTER (0xff). But
reg_addr->reg_report_rate is initialized to 0x00 by devm_kzalloc() (in
edt_ft5x06_ts_probe()) and not changed thereafter. So the checks do
not work and an access to register 0x00 is done.

Fix by setting reg_addr->reg_report_rate to NO_REGISTER.

Also fix the only place where reg_report_rate is checked against zero
instead of NO_REGISTER.
Signed-off-by: NLuca Ceresoli <luca@lucaceresoli.net>
Signed-off-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/touchscreen/edt-ft5x06.c

@@ -593,7 +593,7 @@ static int edt_ft5x06_work_mode(struct edt_ft5x06_ts_data *tsdata)
 				  tsdata->gain);
 	edt_ft5x06_register_write(tsdata, reg_addr->reg_offset,
 				  tsdata->offset);
-	if (reg_addr->reg_report_rate)
+	if (reg_addr->reg_report_rate != NO_REGISTER)
 		edt_ft5x06_register_write(tsdata, reg_addr->reg_report_rate,
 				  tsdata->report_rate);
 
@@ -874,6 +874,7 @@ edt_ft5x06_ts_set_regs(struct edt_ft5x06_ts_data *tsdata)
 
 	case M09:
 		reg_addr->reg_threshold = M09_REGISTER_THRESHOLD;
+		reg_addr->reg_report_rate = NO_REGISTER;
 		reg_addr->reg_gain = M09_REGISTER_GAIN;
 		reg_addr->reg_offset = M09_REGISTER_OFFSET;
 		reg_addr->reg_num_x = M09_REGISTER_NUM_X;