ARM bootblock approach

This lays out the groundwork for using a proper bootblock on ARM.
Currently we bypass the bootblock entirely and go straight to
romstage. However we want to utilize CBFS to maximize flexibility
of placing code without relying on a lot of magic numbers which
will break depending on the SoC in use.

Change-Id: I9cc2a8191d2db38b27b6363ba673e5a360de9684
Signed-off-by: Stefan Reinauer <reinauer@google.com>
Signed-off-by: David Hendricks <dhendrix@chromium.org>
Reviewed-on: http://review.coreboot.org/2118
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>

src/cpu/samsung/exynos5250/Kconfig

@@ -1,10 +1,3 @@
-config BOOTBLOCK_OFFSET
-	hex "Bootblock offset"
-	default 0x3400
-	help
-	  This is where the Coreboot bootblock resides. For Exynos5250,
-	  this value is pre-determined by the vendor-provided BL1.
-
 config EXYNOS_ACE_SHA
 	bool
 	default n