Input: powermate - replace GFP_ATOMIC with GFP_KERNEL in powermate_alloc_buffers()

powermate_alloc_buffers() is never called in atomic context. It calls
usb_alloc_coherent() with GFP_ATOMIC, which is not necessary. GFP_ATOMIC
can be replaced with GFP_KERNEL.

This is found by a static analysis tool named DCNS written by myself.
Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/misc/powermate.c

@@ -277,7 +277,7 @@ static int powermate_input_event(struct input_dev *dev, unsigned int type, unsig
 static int powermate_alloc_buffers(struct usb_device *udev, struct powermate_device *pm)
 {
 	pm->data = usb_alloc_coherent(udev, POWERMATE_PAYLOAD_SIZE_MAX,
-				      GFP_ATOMIC, &pm->data_dma);
+				      GFP_KERNEL, &pm->data_dma);
 	if (!pm->data)
 		return -1;