Input: ili210x - add support for polling mode

Input: ili210x - add support for polling mode

There are designs incorporating Ilitek ILI2xxx touch controller that
do not connect interrupt pin, for example Waveshare 13.3" DSI display.
To support such systems use polling mode for the input device when I2C
client does not have interrupt assigned to it.

Factor out ili210x_firmware_update_noirq() to allow conditional scoped
guard around this code. The scoped guard has to be applied only in case
the IRQ line is connected, and not applied otherwise.

Reviewed-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
Link: https://patch.msgid.link/20260121230736.114623-2-marek.vasut+renesas@mailbox.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>