Convert CONFIG_CMD_SF_TEST to Kconfig

This converts the following to Kconfig:
   CONFIG_CMD_SF_TEST

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
diff --git a/configs/sandbox_defconfig b/configs/sandbox_defconfig
index a1844d3..349d3c7 100644
--- a/configs/sandbox_defconfig
+++ b/configs/sandbox_defconfig
@@ -41,6 +41,7 @@
 CONFIG_CMD_REMOTEPROC=y
 CONFIG_CMD_GPIO=y
 CONFIG_CMD_PCI=y
+CONFIG_CMD_READ=y
 CONFIG_CMD_TFTPPUT=y
 CONFIG_CMD_TFTPSRV=y
 CONFIG_CMD_RARP=y
@@ -193,6 +194,3 @@
 CONFIG_UT_TIME=y
 CONFIG_UT_DM=y
 CONFIG_UT_ENV=y
-CONFIG_CMD_MTDPARTS=y
-CONFIG_CMD_MTDPARTS_SPREAD=y
-CONFIG_CMD_READ=y