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/omap5_uevm_defconfig b/configs/omap5_uevm_defconfig
index c43418a..52f3784 100644
--- a/configs/omap5_uevm_defconfig
+++ b/configs/omap5_uevm_defconfig
@@ -47,6 +47,7 @@
 CONFIG_MMC_OMAP_HS=y
 CONFIG_DM_ETH=y
 CONFIG_SCSI=y
+CONFIG_SCSI_AHCI_PLAT=y
 CONFIG_CONS_INDEX=3
 CONFIG_SYS_NS16550=y
 CONFIG_USB=y