cpu: Add initial support for Allwinner A10 SoC

Add minimal support needed to get a bootblock capable of initialising
a serial console.

Change-Id: I50dd85544549baf9c5ea0aa3b4296972136c02a4
Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Reviewed-on: http://review.coreboot.org/4549
Tested-by: build bot (Jenkins)
Reviewed-by: David Hendricks <dhendrix@chromium.org>
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

src/cpu/Kconfig

@@ -3,6 +3,7 @@
 # (See also src/Kconfig)
 if ARCH_ARMV7
 
+source src/cpu/allwinner/Kconfig
 source src/cpu/armltd/Kconfig
 source src/cpu/samsung/Kconfig
 source src/cpu/ti/Kconfig