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/board/ti/common/Kconfig b/board/ti/common/Kconfig
index adf73ab..77c92a1 100644
--- a/board/ti/common/Kconfig
+++ b/board/ti/common/Kconfig
@@ -1,3 +1,6 @@
+config SPL_ENV_SUPPORT
+	default y
+
 config TI_I2C_BOARD_DETECT
 	bool "Support for Board detection for TI platforms"
 	help