defconfig: firefly-rk3399: fix pinctrl config option

The option is named PINCTRL_ROCKCHIP_RK3399 not ROCKCHIP_RK3399_PINCTRL.
Set the correct option.
Signed-off-by: NHeiko Stuebner <heiko@sntech.de>
Acked-by: NSimon Glass <sjg@chromium.org>

configs/firefly-rk3399_defconfig

@@ -39,7 +39,7 @@ CONFIG_ETH_DESIGNWARE=y
 CONFIG_GMAC_ROCKCHIP=y
 CONFIG_PINCTRL=y
 CONFIG_SPL_PINCTRL=y
-CONFIG_ROCKCHIP_RK3399_PINCTRL=y
+CONFIG_PINCTRL_ROCKCHIP_RK3399=y
 CONFIG_DM_PMIC=y
 CONFIG_PMIC_RK8XX=y
 CONFIG_REGULATOR_PWM=y