ata: Migrate CONFIG_SCSI_AHCI to Kconfig

And use 'imply' liberally.

Signed-off-by: Tuomas Tynkkynen <tuomas.tynkkynen@iki.fi>
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index e50ba93..7390995 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -850,6 +850,7 @@
 	select SUPPORT_SPL
 	select ARCH_MISC_INIT
 	imply SCSI
+	imply SCSI_AHCI
 	help
 	  Support for Freescale LS2080AQDS platform
 	  The LS2080A Development System (QDS) is a high-performance
@@ -865,6 +866,7 @@
 	select SUPPORT_SPL
 	select ARCH_MISC_INIT
 	imply SCSI
+	imply SCSI_AHCI
 	help
 	  Support for Freescale LS2080ARDB platform.
 	  The LS2080A Reference design board (RDB) is a high-performance
@@ -926,6 +928,7 @@
 	select ARM64
 	select BOARD_LATE_INIT
 	imply SCSI
+	imply SCSI_AHCI
 	help
 	  Support for Freescale LS1012ARDB platform.
 	  The LS1012A Reference design board (RDB) is a high-performance