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/chromebox_panther_defconfig b/configs/chromebox_panther_defconfig
index 0d65a90..51a934f 100644
--- a/configs/chromebox_panther_defconfig
+++ b/configs/chromebox_panther_defconfig
@@ -36,6 +36,7 @@
 CONFIG_OF_CONTROL=y
 CONFIG_REGMAP=y
 CONFIG_SYSCON=y
+CONFIG_SCSI=y
 CONFIG_CROS_EC=y
 CONFIG_CROS_EC_LPC=y
 CONFIG_SPI_FLASH=y