feat(allwinner): allow to skip PMIC regulator setup

For somewhat historical reasons we are doing some initial PMIC regulator
setup in BL31, as U-Boot does not (yet) have a PMIC driver. This worked
fine so far, but there is at least one board (OrangePi 3) that gets upset,
because the Ethernet PHY needs some *coordinated* bringup of *two*
regulators.

To avoid custom hacks, let's introduce a build option to keep doing the
regulator setup in TF-A. Defining SUNXI_SETUP_REGULATORS to 0 will break
support for some devices on some boards in U-Boot (Ethernet and HDMI),
but will allow to bring up the OrangePi 3 in Linux correctly. We keep
the default at 1 to not change the behaviour for all other boards.

After U-Boot gained proper PMIC support at some point in the future, we
will probably change the default to 0, to get rid of the less optimal
PMIC code in TF-A.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Change-Id: Ie8e2583d0396f6eeaae8ffe6b6190f27db63e2a7
diff --git a/plat/allwinner/common/allwinner-common.mk b/plat/allwinner/common/allwinner-common.mk
index 61ae9b6..34fdaf6 100644
--- a/plat/allwinner/common/allwinner-common.mk
+++ b/plat/allwinner/common/allwinner-common.mk
@@ -61,6 +61,10 @@
 				${AW_PLAT}/common/sunxi_scpi_pm.c
 endif
 
+SUNXI_SETUP_REGULATORS	?=	1
+$(eval $(call assert_boolean,SUNXI_SETUP_REGULATORS))
+$(eval $(call add_define,SUNXI_SETUP_REGULATORS))
+
 # The bootloader is guaranteed to only run on CPU 0 by the boot ROM.
 COLD_BOOT_SINGLE_CPU		:=	1