input: raspberrypi-ts: Release firmware handle when not needed

There is no use for the firmware interface after getting the touch
buffer address, so release it.

Signed-off-by: Nicolas Saenz Julienne <[e-mail]>
Acked-by: Dmitry Torokhov <[e-mail]>
Reviewed-by: Florian Fainelli <[e-mail]>

drivers/input/touchscreen/raspberrypi-ts.c

···
 	touchbuf = (u32)ts->fw_regs_phys;
 	error = rpi_firmware_property(fw, RPI_FIRMWARE_FRAMEBUFFER_SET_TOUCHBUF,
 				      &touchbuf, sizeof(touchbuf));
-
+	rpi_firmware_put(fw);
 	if (error || touchbuf != 0) {
 		dev_warn(dev, "Failed to set touchbuf, %d\n", error);
 		return error;