fix(plat/marvell/a8k): Correctly set include directories for individual targets

Do not set all include directories, including those for external targets
in one PLAT_INCLUDES variable.

Instead split them into variables:
* $(PLAT_INCLUDES) for all TF-A BL images
* BLE target specific $(PLAT_INCLUDES) only for Marvell BLE image
* $(MV_DDR_INCLUDES) for targets in external Marvell mv-ddr-marvell tree

Include directory $(CURDIR)/drivers/marvell is required by TF-A BL
images, so move it from ble.mk to a8k_common.mk.

Include directory $(MV_DDR_PATH) is needed only by Marvell BLE image, so
move it into BLE target specific $(PLAT_INCLUDES) variable.

And remaining include directories specified in ble.mk are needed only
for building external dependences from Marvell mv-ddr tree, so move them
into $(MV_DDR_INCLUDES) variable and correctly use it in $(MV_DDR_LIB)
target.

Signed-off-by: Pali Rohár <pali@kernel.org>
Change-Id: I331f7de675dca2bc70733d56b768f00d56ae4a67
diff --git a/plat/marvell/armada/a8k/common/a8k_common.mk b/plat/marvell/armada/a8k/common/a8k_common.mk
index 90883f2..773b912 100644
--- a/plat/marvell/armada/a8k/common/a8k_common.mk
+++ b/plat/marvell/armada/a8k/common/a8k_common.mk
@@ -82,6 +82,7 @@
 
 PLAT_INCLUDES		:=	-I$(BOARD_DIR)				\
 				-I$(BOARD_DIR)/board			\
+				-I$(CURDIR)/drivers/marvell		\
 				-I$(PLAT_COMMON_BASE)/include		\
 				-I$(PLAT_INCLUDE_BASE)/common