arm: highbank: Enable OF_CONTROL

All Calxeda machines are actually a poster book example of device tree
usage: the DT is loaded from flash by the management processor into
DRAM, the memory node is populated with the detected DRAM size and this
DT is then handed over to the kernel.
So it's a shame that U-Boot didn't participate in this chain, but
fortunately this is easy to fix:

Define CONFIG_OF_CONTROL and CONFIG_OF_BOARD, and provide a trivial
function to tell U-Boot about the (fixed) location of the DTB in DRAM.
Then enable DM_SERIAL, to let the PL011 driver pick up the UART platform
data from the DT. Also define AHCI, to bring this driver into the driver
model world as well.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 15b8454..3586426 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -711,7 +711,14 @@
 config ARCH_HIGHBANK
 	bool "Calxeda Highbank"
 	select CPU_V7A
-	select PL011_SERIAL
+	select PL01X_SERIAL
+	select DM
+	select DM_SERIAL
+	select OF_CONTROL
+	select OF_BOARD
+	select CLK
+	select CLK_CCF
+	select AHCI
 
 config ARCH_INTEGRATOR
 	bool "ARM Ltd. Integrator family"