rockchip: puma-rk3399: allow loading environment from SPI-NOR flash

There's a SPI-NOR flash available from which SPL and U-Boot proper can
be booted, it makes sense to also allow this medium to store U-Boot
environment so let's enable it.

The Device Tree advertises a max frequency of 50MHz so let's set the
config option appropriately.

Cc: Quentin Schulz <foss+uboot@0leil.net>
Signed-off-by: Quentin Schulz <quentin.schulz@theobroma-systems.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
diff --git a/configs/puma-rk3399_defconfig b/configs/puma-rk3399_defconfig
index 1b0bf88..f62cfc9 100644
--- a/configs/puma-rk3399_defconfig
+++ b/configs/puma-rk3399_defconfig
@@ -54,6 +54,8 @@
 CONFIG_OF_SPL_REMOVE_PROPS="interrupt-parent assigned-clocks assigned-clock-rates assigned-clock-parents"
 CONFIG_ENV_OVERWRITE=y
 CONFIG_ENV_IS_IN_MMC=y
+CONFIG_ENV_IS_IN_SPI_FLASH=y
+CONFIG_ENV_SPI_MAX_HZ=50000000
 CONFIG_SYS_RELOC_GD_ENV_ADDR=y
 CONFIG_SYS_MMC_ENV_DEV=1
 CONFIG_ENV_VARS_UBOOT_RUNTIME_CONFIG=y