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/broadwell/Kconfig b/arch/x86/cpu/broadwell/Kconfig
index bc2dba2..42018dc 100644
--- a/arch/x86/cpu/broadwell/Kconfig
+++ b/arch/x86/cpu/broadwell/Kconfig
@@ -13,6 +13,7 @@
 	imply ICH_SPI
 	imply INTEL_BROADWELL_GPIO
 	imply SCSI
+	imply SCSI_AHCI
 	imply SPI_FLASH
 	imply USB
 	imply USB_EHCI_HCD