Input: pxa27x_keypad - fix NULL pointer dereference

A NULL pointer dereference exception occurs in the driver probe function when
device tree is used.  The pdata pointer will be NULL in this case, but the code
dereferences it in all cases.  When device tree is used, a platform data
structure is allocated and initialized, and in all cases this pointer is copied
to the driver's private data, so the variable being tested should be accessed
through the driver's private data structure.
Signed-off-by: NMike Dunn <mikedunn@newsguy.com>
Signed-off-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/keyboard/pxa27x_keypad.c

@@ -786,10 +786,17 @@ static int pxa27x_keypad_probe(struct platform_device *pdev)
 	input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_REP);
 	input_set_capability(input_dev, EV_MSC, MSC_SCAN);
 
-	if (pdata)
+	if (pdata) {
 		error = pxa27x_keypad_build_keycode(keypad);
-	else
+	} else {
 		error = pxa27x_keypad_build_keycode_from_dt(keypad);
+		/*
+		 * Data that we get from DT resides in dynamically
+		 * allocated memory so we need to update our pdata
+		 * pointer.
+		 */
+		pdata = keypad->pdata;
+	}
 	if (error) {
 		dev_err(&pdev->dev, "failed to build keycode\n");
 		goto failed_put_clk;