sandbox: Enable SCSI for all builds

This will be needed to run unit tests, once the SCSI code is used for USB
as well. Enable it for all sandbox builds.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/configs/sandbox_flattree_defconfig b/configs/sandbox_flattree_defconfig
index 4b18c24..a834402 100644
--- a/configs/sandbox_flattree_defconfig
+++ b/configs/sandbox_flattree_defconfig
@@ -174,6 +174,10 @@
 CONFIG_DM_RESET=y
 CONFIG_SANDBOX_RESET=y
 CONFIG_DM_RTC=y
+CONFIG_SCSI=y
+CONFIG_SCSI_AHCI_PLAT=y
+CONFIG_SYS_SCSI_MAX_SCSI_ID=8
+CONFIG_SYS_SCSI_MAX_LUN=4
 CONFIG_SANDBOX_SERIAL=y
 CONFIG_SOUND=y
 CONFIG_SOUND_SANDBOX=y