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/efi-x86_defconfig b/configs/efi-x86_defconfig
index 789c5ce..a23d402 100644
--- a/configs/efi-x86_defconfig
+++ b/configs/efi-x86_defconfig
@@ -11,6 +11,7 @@
 # CONFIG_CMD_IMLS is not set
 CONFIG_CMD_PART=y
 CONFIG_CMD_SF=y
+# CONFIG_CMD_SF_TEST is not set
 CONFIG_CMD_SPI=y
 CONFIG_CMD_USB=y
 CONFIG_CMD_GPIO=y