When CONFIG_INPUT_POLLDEV is disabled, we get a link error:
drivers/input/touchscreen/raspberrypi-ts.o: In function `rpi_ts_probe':
raspberrypi-ts.c:(.text+0xec): undefined reference to `devm_input_allocate_polled_device'
raspberrypi-ts.c:(.text+0xec): relocation truncated to fit: R_AARCH64_CALL26 against undefined symbol `devm_input_allocate_polled_device'
raspberrypi-ts.c:(.text+0x19c): undefined reference to `input_register_polled_device'
raspberrypi-ts.c:(.text+0x19c): relocation truncated to fit: R_AARCH64_CALL26 against undefined symbol `input_register_polled_device'
Select that symbol like we do from the other similar drivers.