pinctrl: ti-iodelay: remove redundant unused variable dev

The pointer dev is being assigned but is never used, hence it is
redundant and can be removed. Cleans up clang warnings:

drivers/pinctrl/ti/pinctrl-ti-iodelay.c:582:2: warning: Value stored
to 'dev' is never read
drivers/pinctrl/ti/pinctrl-ti-iodelay.c:701:2: warning: Value stored
to 'dev' is never read

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>