scsi: Move drivers into new drivers/scsi directory

At present we have the SCSI drivers in the drivers/block and common/
directories. It is better to split them out into their own place. Use
drivers/scsi which is what Linux does.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/drivers/Kconfig b/drivers/Kconfig
index 63e4034..2e03133 100644
--- a/drivers/Kconfig
+++ b/drivers/Kconfig
@@ -72,6 +72,8 @@
 
 source "drivers/rtc/Kconfig"
 
+source "drivers/scsi/Kconfig"
+
 source "drivers/serial/Kconfig"
 
 source "drivers/sound/Kconfig"