ata: Migrate CONFIG_SCSI_AHCI to Kconfig

And use 'imply' liberally.

Signed-off-by: Tuomas Tynkkynen <tuomas.tynkkynen@iki.fi>
diff --git a/arch/x86/cpu/ivybridge/Kconfig b/arch/x86/cpu/ivybridge/Kconfig
index c214ea0..85ea6c9 100644
--- a/arch/x86/cpu/ivybridge/Kconfig
+++ b/arch/x86/cpu/ivybridge/Kconfig
@@ -14,6 +14,7 @@
 	imply ICH_SPI
 	imply INTEL_ICH6_GPIO
 	imply SCSI
+	imply SCSI_AHCI
 	imply SPI_FLASH
 	imply USB
 	imply USB_EHCI_HCD