armv7: Reserve space BL1 and checksum header by specifying bootblock offset.

Not all ARM systems need "BL1", and the layout of BL* and bootblock may be
different (ex, Exynos 5250 may use a new BL1 with variable length checksum
header).

To support that better, define the real base address (and ROM offset) of boot
block, and then we can post-processing ROM image file by filling data / checksum
and any other information.

Change-Id: I0e3105e52500b6b457371ad33a9aa546acf28928
Signed-off-by: Hung-Te Lin <hungte@chromium.org>
Signed-off-by: Gabe Black <gabeblack@chromium.org>
Reviewed-on: http://review.coreboot.org/3664
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

src/mainboard/emulation/qemu-armv7/Kconfig

@@ -81,6 +81,10 @@ config ROMSTAGE_SIZE
 	hex
 	default 0x20000
 
+config BOOTBLOCK_ROM_OFFSET
+	hex
+	default 0x0
+
 config CBFS_HEADER_ROM_OFFSET
 	hex
 	default 0x0100000