allwinner: Unify platform.mk files

For the two different platforms we support in the Allwinner port we
mostly rely on header files covering the differences. This leads to the
platform.mk files in the respective directories to be almost identical.

To avoid further divergence and make sure that one platform doesn't
break accidentally, let's create a shared allwinner-common.mk file and
include that from the platform directory.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
diff --git a/plat/allwinner/common/allwinner-common.mk b/plat/allwinner/common/allwinner-common.mk
new file mode 100644
index 0000000..15888a8
--- /dev/null
+++ b/plat/allwinner/common/allwinner-common.mk
@@ -0,0 +1,54 @@
+#
+# Copyright (c) 2017-2018, ARM Limited and Contributors. All rights reserved.
+#
+# SPDX-License-Identifier: BSD-3-Clause
+#
+
+include lib/xlat_tables_v2/xlat_tables.mk
+
+AW_PLAT			:=	plat/allwinner
+
+PLAT_INCLUDES		:=	-Iinclude/plat/arm/common		\
+				-Iinclude/plat/arm/common/aarch64	\
+				-I${AW_PLAT}/common/include		\
+				-I${AW_PLAT}/${PLAT}/include
+
+PLAT_BL_COMMON_SOURCES	:=	drivers/console/${ARCH}/console.S	\
+				drivers/ti/uart/${ARCH}/16550_console.S	\
+				${XLAT_TABLES_LIB_SRCS}			\
+				${AW_PLAT}/common/plat_helpers.S	\
+				${AW_PLAT}/common/sunxi_common.c
+
+BL31_SOURCES		+=	drivers/arm/gic/common/gic_common.c	\
+				drivers/arm/gic/v2/gicv2_helpers.c	\
+				drivers/arm/gic/v2/gicv2_main.c		\
+				drivers/delay_timer/delay_timer.c	\
+				drivers/delay_timer/generic_delay_timer.c \
+				lib/cpus/${ARCH}/cortex_a53.S		\
+				plat/common/plat_gicv2.c		\
+				plat/common/plat_psci_common.c		\
+				${AW_PLAT}/common/sunxi_bl31_setup.c	\
+				${AW_PLAT}/common/sunxi_cpu_ops.c	\
+				${AW_PLAT}/common/sunxi_pm.c		\
+				${AW_PLAT}/${PLAT}/sunxi_power.c	\
+				${AW_PLAT}/common/sunxi_security.c	\
+				${AW_PLAT}/common/sunxi_topology.c
+
+# The bootloader is guaranteed to only run on CPU 0 by the boot ROM.
+COLD_BOOT_SINGLE_CPU		:=	1
+
+# Enable workarounds for Cortex-A53 errata. Allwinner uses at least r0p4.
+ERRATA_A53_835769		:=	1
+ERRATA_A53_843419		:=	1
+ERRATA_A53_855873		:=	1
+
+MULTI_CONSOLE_API		:=	1
+
+# The reset vector can be changed for each CPU.
+PROGRAMMABLE_RESET_ADDRESS	:=	1
+
+# Allow mapping read-only data as execute-never.
+SEPARATE_CODE_AND_RODATA	:=	1
+
+# BL31 gets loaded alongside BL33 (U-Boot) by U-Boot's SPL
+RESET_TO_BL31			:=	1