AMD CIMx SB800: Enable AHCI mode for SATA controller by default

The current default is IDE mode which is slower compared to AHCI
mode. Therefore use AHCI mode by default.

A similar change was made for AMD Persimmon in commit
»Enable SATA AHCI for faster boot with SeaBIOS.« (96be74c7) [1]
but was indirectly reverted by »sb800: Add sata ahci/raid mode
kconfig option« (d4a0e7d0) [2].

[1] http://review.coreboot.org/220
[2] http://review.coreboot.org/225

Change-Id: I4fa31b0a3280891e7a3f37675ae8415205818947
Signed-off-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-on: http://review.coreboot.org/2661
Tested-by: build bot (Jenkins)
Reviewed-by: Marc Jones <marc.jones@se-eng.com>
diff --git a/src/southbridge/amd/cimx/sb800/Kconfig b/src/southbridge/amd/cimx/sb800/Kconfig
index 2c9ab18..53fad3c 100644
--- a/src/southbridge/amd/cimx/sb800/Kconfig
+++ b/src/southbridge/amd/cimx/sb800/Kconfig
@@ -46,7 +46,7 @@
 
 choice
 	prompt "SATA Mode"
-	default SB800_SATA_IDE
+	default SB800_SATA_AHCI
 	help
 	  Select the mode in which SATA should be driven. NATIVE AHCI, or RAID.
 	  The default is NATIVE.