plat: marvell: a8k: extend includes to take advantage of the phy_porting_layer

The phy porting layer uses defaults defined in
"phy-default-porting-layer.h" when board specific file
"phy-porting-layer.h" is not found. Because of the regression the board
specific directory was not included, therefore all boards used default
parameters.

Change-Id: I66e5e6eb8a39cca5aeeb4de6dab2ceddc39c1e31
Signed-off-by: Grzegorz Jaszczyk <jaz@semihalf.com>

plat/marvell/armada/a8k/common/a8k_common.mk

@@ -52,6 +52,7 @@ MARVELL_GIC_SOURCES	:=	drivers/arm/gic/common/gic_common.c	\
 				plat/common/plat_gicv2.c
 
 PLAT_INCLUDES		:=	-I$(BOARD_DIR)				\
+				-I$(BOARD_DIR)/board			\
 				-I$(PLAT_COMMON_BASE)/include		\
 				-I$(PLAT_INCLUDE_BASE)/common