Convert CONFIG_SPL_ENV_SUPPORT to Kconfig

Move this option to Kconfig and tidy up existing uses.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/configs/P1010RDB-PB_NAND_defconfig b/configs/P1010RDB-PB_NAND_defconfig
index e8b1d5d..09155b6 100644
--- a/configs/P1010RDB-PB_NAND_defconfig
+++ b/configs/P1010RDB-PB_NAND_defconfig
@@ -1,4 +1,5 @@
 CONFIG_PPC=y
+CONFIG_SPL_DRIVERS_MISC_SUPPORT=y
 CONFIG_MPC85xx=y
 CONFIG_TARGET_P1010RDB=y
 CONFIG_FIT=y
@@ -9,7 +10,7 @@
 CONFIG_BOOTDELAY=10
 CONFIG_SPL=y
 CONFIG_TPL=y
-CONFIG_SPL_DRIVERS_MISC_SUPPORT=y
+CONFIG_TPL_ENV_SUPPORT=y
 CONFIG_HUSH_PARSER=y
 CONFIG_CMD_MMC=y
 CONFIG_CMD_SF=y