Convert CONFIG_CMD_SCSI to Kconfig

This converts the following to Kconfig:
   CONFIG_CMD_SCSI

Also update the Makefile to use CONFIG_CMD_SCSI instead of CONFIG_SCSI to
enable the command, fixing an earlier error.

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>
[trini: Rework to default y if SCSI, drop cl-som-am57x which did not use
CMD_SCSI for real]
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/cmd/Kconfig b/cmd/Kconfig
index 9efc2cf..cf89fd7 100644
--- a/cmd/Kconfig
+++ b/cmd/Kconfig
@@ -1290,6 +1290,15 @@
 	    reiserls - list files
 	    reiserload - load a file
 
+config CMD_SCSI
+	bool "scsi - Access to SCSI devices"
+	default y if SCSI
+	help
+	  This provides a 'scsi' command which provides access to SCSI (Small
+	  Computer System Interface) devices. The command provides a way to
+	  scan the bus, reset the bus, read and write data and get information
+	  about devices.
+
 endmenu
 
 menu "Debug commands"