gpio: ts4800: Drop redundant code to set already initialized gpio_chip fields

Both chip->base and chip->label are correctly set by bgpio_init().

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Tested-by: Julien Grossholtz <julien.grossholtz@savoirfairelinux.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>