Convert CONFIG_SCSI to Kconfig

This converts the following to Kconfig:
   CONFIG_SCSI

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/configs/chromebook_samus_defconfig b/configs/chromebook_samus_defconfig
index 3e12bea..ab2d27e 100644
--- a/configs/chromebook_samus_defconfig
+++ b/configs/chromebook_samus_defconfig
@@ -40,6 +40,7 @@
 CONFIG_OF_CONTROL=y
 CONFIG_REGMAP=y
 CONFIG_SYSCON=y
+CONFIG_SCSI=y
 CONFIG_CPU=y
 CONFIG_INTEL_BROADWELL_GPIO=y
 CONFIG_CROS_EC=y