pinctrl: nand: meson-gxbb: fix missing data pins

The data pin 0-7 of the NAND controller are actually missing from
the nand pinctrl group, so we fix it here.

Fixes: cd1e3b01 ("pinctrl: amlogic: gxbb: add nand pins")
Reported-by: Liang Yang <liang.yang@amlogic.com>
Signed-off-by: Yixun Lan <yixun.lan@amlogic.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>