zephyr: Add Hexiwear k64 support

The hexiwear k64 is very similar to the frdm_k64, as far as mcuboot is
concerned.  The partitions are now defined in DTS in Zephyr, and this
target file just needs the device name, sector size, and alignment.

Signed-off-by: David Brown <david.brown@linaro.org>

boot/zephyr/targets/hexiwear_k64.h

@@ -0,0 +1,24 @@
+/*
+ * Copyright (c) 2017 Linaro
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * @file
+ * @brief Bootloader device specific configuration.
+ */
+
+#define FLASH_DRIVER_NAME		CONFIG_SOC_FLASH_MCUX_DEV_NAME
+#define FLASH_ALIGN			8
+#define FLASH_AREA_IMAGE_SECTOR_SIZE	0x01000