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/drivers/ata/Kconfig b/drivers/ata/Kconfig
index 1adf4dc..ce6907e 100644
--- a/drivers/ata/Kconfig
+++ b/drivers/ata/Kconfig
@@ -135,6 +135,16 @@
 	  Enable this driver to support the SIL3131, SIL3132 and SIL3124
 	  SATA controllers.
 
+config SYS_SATA_MAX_DEVICE
+	int "Maximum number of SATA devices"
+	depends on !AHCI || FSL_SATA || SATA_MV
+	help
+	  Sets the maximum number of SATA devices which can be supported
+	  by U-Boot.
+
+	  This is only partially converted to driver model. See sata_bread()
+	  for example, which shows where the conversion needs to be completed.
+
 endif # SATA
 
 endmenu