boot/zephyr: Added single-slot Zephyr-RTOS test build

Added configuration for build in Zephyr-RTOS CI MCUBoot
in CONFIG_SINGLE_APPLICATION_SLOT=y mode.

Signed-off-by: Andrzej Puzdrowski <andrzej.puzdrowski@nordicsemi.no>
diff --git a/boot/zephyr/boards/nrf52840_single_slot.overlay b/boot/zephyr/boards/nrf52840_single_slot.overlay
new file mode 100644
index 0000000..8e7cc33
--- /dev/null
+++ b/boot/zephyr/boards/nrf52840_single_slot.overlay
@@ -0,0 +1,26 @@
+/*
+ * Copyright (c) 2020 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/delete-node/ &boot_partition;
+/delete-node/ &slot0_partition;
+/delete-node/ &slot1_partition;
+
+&flash0 {
+	partitions {
+			compatible = "fixed-partitions";
+			#address-cells = <1>;
+			#size-cells = <1>;
+
+			boot_partition: partition@0 {
+				label = "mcuboot";
+				reg = <0x000000000 0x00010000>;
+			};
+			slot0_partition: partition@10000 {
+				label = "image-0";
+				reg = <0x000010000 0x0000E8000>;
+			};
+	};
+};
diff --git a/boot/zephyr/sample.yaml b/boot/zephyr/sample.yaml
index 6c41d28..048a588 100644
--- a/boot/zephyr/sample.yaml
+++ b/boot/zephyr/sample.yaml
@@ -18,3 +18,8 @@
       DTC_OVERLAY_FILE=./boards/nrf52840_big.overlay
     platform_allow:  nrf52840dk_nrf52840
     tags: bootloader_mcuboot
+  sample.bootloader.mcuboot.single_slot:
+    extra_args: OVERLAY_CONFIG=./single_slot.conf
+      DTC_OVERLAY_FILE=./boards/nrf52840_single_slot.overlay
+    platform_allow:  nrf52840dk_nrf52840
+    tags: bootloader_mcuboot
diff --git a/boot/zephyr/single_slot.conf b/boot/zephyr/single_slot.conf
new file mode 100644
index 0000000..34cc92a
--- /dev/null
+++ b/boot/zephyr/single_slot.conf
@@ -0,0 +1 @@
+CONFIG_SINGLE_APPLICATION_SLOT=y