rockchip: rockpro64: enable DM_KEYBOARD

USB stack uses DM so DM_KEYBOARD is needed to get USB keyboard working.

Signed-off-by: Marcin Juszkiewicz <marcin@juszkiewicz.com.pl>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
diff --git a/configs/rockpro64-rk3399_defconfig b/configs/rockpro64-rk3399_defconfig
index ffa4f9d..8c4b2f3 100644
--- a/configs/rockpro64-rk3399_defconfig
+++ b/configs/rockpro64-rk3399_defconfig
@@ -28,6 +28,7 @@
 CONFIG_SYS_RELOC_GD_ENV_ADDR=y
 CONFIG_ROCKCHIP_GPIO=y
 CONFIG_SYS_I2C_ROCKCHIP=y
+CONFIG_DM_KEYBOARD=y
 CONFIG_MISC=y
 CONFIG_ROCKCHIP_EFUSE=y
 CONFIG_MMC_DW=y