"struct tca6416_drv_data" is unused.
Remove it.

Found with cppcheck, unusedStructMember.
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/3e6fd1d0875ef3c90ecaab7adf7fd4a5e8e6f708.1714541432.git.christophe.jaillet@wanadoo.frSigned-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>