Convert CONFIG_SCSI_AHCI_PLAT et al to Kconfig

This converts the following to Kconfig:
   CONFIG_SCSI_AHCI_PLAT
   CONFIG_SYS_SCSI_MAX_SCSI_ID
   CONFIG_SYS_SCSI_MAX_LUN
   CONFIG_SYS_SATA_MAX_DEVICE

Drop CONFIG_SCSI for everything except the sandbox build. We only need
one build for tests.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Stefan Roese <sr@denx.de>
diff --git a/configs/netspace_v2_defconfig b/configs/netspace_v2_defconfig
index 6b08865..b6bf9d7 100644
--- a/configs/netspace_v2_defconfig
+++ b/configs/netspace_v2_defconfig
@@ -49,6 +49,7 @@
 CONFIG_DM=y
 CONFIG_SATA=y
 CONFIG_SATA_MV=y
+CONFIG_SYS_SATA_MAX_DEVICE=1
 CONFIG_KIRKWOOD_GPIO=y
 CONFIG_SYS_I2C_LEGACY=y
 CONFIG_SYS_I2C_MVTWSI=y