ata: Migrate CONFIG_SCSI_AHCI to Kconfig

And use 'imply' liberally.

Signed-off-by: Tuomas Tynkkynen <tuomas.tynkkynen@iki.fi>
diff --git a/configs/Linksprite_pcDuino3_defconfig b/configs/Linksprite_pcDuino3_defconfig
index a54f9de..1392d1f 100644
--- a/configs/Linksprite_pcDuino3_defconfig
+++ b/configs/Linksprite_pcDuino3_defconfig
@@ -14,6 +14,7 @@
 # CONFIG_SPL_DOS_PARTITION is not set
 # CONFIG_SPL_ISO_PARTITION is not set
 # CONFIG_SPL_EFI_PARTITION is not set
+CONFIG_SCSI_AHCI=y
 CONFIG_DM_MMC=y
 CONFIG_ETH_DESIGNWARE=y
 CONFIG_SUN7I_GMAC=y