marvell: Move BLE from external repo to the platform folder

The BLE is the pre-TF-A boot stage required by Marvell Armada
BootROM for bringing up DRAM and allow the boot image copy to it.
Since this is not a standard boot level and only uses the TF-A
as a build environment, it was introduced out of source tree.
However it turns out that such remote location introduces additional
complexity to the upstream TF-A build process.
In order to simplify the build environment the BLE source folder
is relocated from the external repository to A8K platform directory.
The build documentation is updated accordingly.

Signed-off-by: Konstantin Porotchkin <kostap@marvell.com>
diff --git a/plat/marvell/a8k/common/ble/ble.mk b/plat/marvell/a8k/common/ble/ble.mk
new file mode 100644
index 0000000..a76083e
--- /dev/null
+++ b/plat/marvell/a8k/common/ble/ble.mk
@@ -0,0 +1,31 @@
+# Copyright (C) 2018 Marvell International Ltd.
+#
+# SPDX-License-Identifier:     BSD-3-Clause
+# https://spdx.org/licenses
+
+MV_DDR_PATH		?=	drivers/marvell/mv_ddr
+
+MV_DDR_LIB		= 	$(CURDIR)/$(BUILD_PLAT)/ble/mv_ddr_lib.a
+LIBC_LIB		=	$(CURDIR)/$(BUILD_PLAT)/lib/libc.a
+BLE_LIBS		= 	$(MV_DDR_LIB) $(LIBC_LIB)
+PLAT_MARVELL		=	plat/marvell
+
+BLE_SOURCES		+= 	$(BLE_PATH)/ble_main.c				\
+				$(BLE_PATH)/ble_mem.S				\
+				drivers/delay_timer/delay_timer.c	\
+				$(PLAT_MARVELL)/common/plat_delay_timer.c
+
+PLAT_INCLUDES		+= 	-I$(MV_DDR_PATH) \
+				-I$(CURDIR)/include/ \
+				-I$(CURDIR)/include/drivers \
+				-I$(CURDIR)/include/lib \
+				-I$(CURDIR)/include/lib/libc \
+				-I$(CURDIR)/include/lib/libc/aarch64 \
+				-I$(CURDIR)/drivers/marvell
+
+BLE_LINKERFILE		:=	$(BLE_PATH)/ble.ld.S
+
+FORCE:
+
+$(MV_DDR_LIB): FORCE
+	@+make -C $(MV_DDR_PATH) --no-print-directory PLAT_INCLUDES="$(PLAT_INCLUDES)" PLATFORM=$(PLAT) ARCH=AARCH64 OBJ_DIR=$(CURDIR)/$(BUILD_PLAT)/ble