elgin-rv1108: Use rk_board_late_init() for GPIO settings

Since commit 8e9a8d0d ("rockchip: elgin-rv1108: use board_early_init_f
for per-boar init") the function that configure the board GPIOs is no
longer called since CONFIG_BOARD_EARLY_INIT_F=y is not selected.

These GPIOs do not need to be configured in such early stagem, so change it
to rk_board_late_init() and also select CONFIG_BOARD_LATE_INIT=y
to fix the regression.

Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
Signed-off-by: Fabio Berton <fabio.berton@ossystems.com.br>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>