plat: marvell: armada: Add new target mrvl_bootimage

This new target builds boot-image.bin binary as described in documentation.
This image does not contain WTMI image and therefore WTP repository is not
required for building.

Having ability to build just this boot-image.bin binary without full
flash-image.bin is useful for A3720 Turris MOX board which does not use
Marvell's WTP and a3700_utils.

To reduce duplicity between a8k and a3k code, define this new target and
also definitions for $(BUILD_PLAT)/$(BOOT_IMAGE) in common include file
marvell_common.mk.

For this purpose it is needed to include plat/marvell/marvell.mk file from
a3700_common.mk unconditionally (and not only when WTP is defined). Now
when common file plat/marvell/marvell.mk does not contain definition for
building $(DOIMAGETOOL), it is possible to move its inclusion at the top of
the a3700_common.mk file.

Signed-off-by: Pali Rohár <pali@kernel.org>
Change-Id: Ic58303b37a1601be9a06ff83b7a279cb7cfc8280
diff --git a/plat/marvell/armada/a8k/common/a8k_common.mk b/plat/marvell/armada/a8k/common/a8k_common.mk
index c827326..58394a4 100644
--- a/plat/marvell/armada/a8k/common/a8k_common.mk
+++ b/plat/marvell/armada/a8k/common/a8k_common.mk
@@ -160,8 +160,6 @@
 	@$(DOIMAGE_LIBS_CHECK)
 	${Q}${MAKE} --no-print-directory -C ${DOIMAGEPATH}
 
-mrvl_flash: ${BUILD_PLAT}/${FIP_NAME} ${DOIMAGETOOL} ${BUILD_PLAT}/ble.bin
-	$(shell truncate -s %128K ${BUILD_PLAT}/bl1.bin)
-	$(shell cat ${BUILD_PLAT}/bl1.bin ${BUILD_PLAT}/${FIP_NAME} > ${BUILD_PLAT}/${BOOT_IMAGE})
+mrvl_flash: ${BUILD_PLAT}/${BOOT_IMAGE} ${DOIMAGETOOL}
 	${DOIMAGETOOL} ${DOIMAGE_FLAGS} ${BUILD_PLAT}/${BOOT_IMAGE} ${BUILD_PLAT}/${FLASH_IMAGE}