config: evb-rk3399: enable pwm regulator

Enable the pwm regulator for evb-rk3399.

Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
Acked-by: Simon Glass <sjg@chromium.org>

configs/evb-rk3399_defconfig

@@ -23,6 +23,7 @@ CONFIG_ROCKCHIP_SDHCI=y
 CONFIG_ROCKCHIP_GPIO=y
 CONFIG_PINCTRL=y
 CONFIG_ROCKCHIP_RK3399_PINCTRL=y
+CONFIG_REGULATOR_PWM=y
 CONFIG_RAM=y
 CONFIG_DEBUG_UART=y
 CONFIG_DEBUG_UART_BASE=0xFF1A0000