gpio: ftgpio010: use device name for gpiochip name & label

Currently, we use just the fixed string "FTGPIO010" as the gpiochip name
for ftgpio010 drivers. Because it's fixed, this means we cannot
distinguish multiple ftgpio010 devices present on a single system.

This change uses the dev_name() instead, which should be unique between
multiple instances.

Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>