stm32mp1: define STM32MP15C-ED1

STM32MP15C-ED1 is the child board plugged on EV1 mother board. ED1 can
be used without its mother board with some interface restrictions
(I.e. no USB-C). This change defines the platform flavor. The several
components (optee_os, tf-a, u-boot, linux) already support ED1 DTS file
identifier.

Signed-off-by: Etienne Carriere <etienne.carriere@linaro.org>
Signed-off-by: Etienne Carriere <etienne.carriere@st.com>
Acked-by: Jerome Forissier <jerome@forissier.org>

br-ext/board/stmicroelectronics/stm32mp1-tz/genimage-STM32MP157C-ED1.cfg

+image sdcard.img {
+	hdimage {
+		gpt = "true"
+	}
+
+	partition fsbl1 {
+		image = "tf-a-stm32mp157c-ed1.stm32"
+		size = 256K
+	}
+
+	partition fsbl2 {
+		image = "tf-a-stm32mp157c-ed1.stm32"
+		size = 256K
+	}
+
+	partition ssbl {
+		image = "u-boot.stm32"
+		size = 2M
+	}
+
+	partition teeh {
+		image = "tee-header_v2.stm32"
+		size = 32K
+	}
+
+	partition teed {
+		image = "tee-pageable_v2.stm32"
+		size = 2M
+	}
+
+	partition teex {
+		image = "tee-pager_v2.stm32"
+		size = 2M
+	}
+
+	partition bootfs {
+		image = "bootfs.ext2"
+		partition-type-uuid = L
+		size = 32M
+		bootable = "yes"
+	}
+
+	partition rootfs {
+		image = "rootfs.ext2"
+		partition-type-uuid = L
+		size = 100M
+	}
+}

br-ext/board/stmicroelectronics/stm32mp1-tz/overlay-STM32MP157C-ED1/boot/extlinux/extlinux.conf

+TIMEOUT 20
+DEFAULT stm32mp15-buildroot
+LABEL stm32mp15-buildroot
+  kernel /boot/uImage
+  devicetree /boot/stm32mp157c-ev1.dtb
+  append root=/dev/mmcblk0p8 rootwait rw console=ttySTM0,115200

stm32mp1.mk

@@ -22,6 +22,9 @@ STM32MP1_DTS_BASENAME	= stm32mp157c-dk2
 else ifeq ($(PLATFORM),stm32mp1-157C_EV1)
 BREXT_FLAVOR		= STM32MP157C-EV1
 STM32MP1_DTS_BASENAME	= stm32mp157c-ev1
+else ifeq ($(PLATFORM),stm32mp1-157C_ED1)
+BREXT_FLAVOR		= STM32MP157C-ED1
+STM32MP1_DTS_BASENAME	= stm32mp157c-ed1
 else
 $(error Unknown PLATFORM $(PLATFORM))
 endif