Support for STM32L0 MCUs and Dragino LGT92 device (#1561)

machine/stm32l0: add support for stm32l0 family and Dragino LGT92 Board

targets/lgt92.json

@@ -0,0 +1,12 @@
+{
+	"inherits": [
+		"stm32l0x2"
+	],
+	"build-tags": [
+		"lgt92"
+	],
+	"linkerscript": "targets/stm32l072czt6.ld",
+	"flash-method": "openocd",
+	"openocd-interface": "stlink-v2",
+	"openocd-target": "stm32f0x"
+}

targets/stm32l072czt6.ld

@@ -0,0 +1,10 @@
+
+MEMORY
+{
+    FLASH_TEXT (rw) : ORIGIN = 0x08000000, LENGTH = 128K
+    RAM (xrw)       : ORIGIN = 0x20000000, LENGTH = 20K
+}
+
+_stack_size = 2K;
+
+INCLUDE "targets/arm.ld"

targets/stm32l0x2.json

@@ -0,0 +1,18 @@
+{
+    "inherits": [
+        "cortex-m"
+    ],
+    "llvm-target": "armv6m-none-eabi",
+    "build-tags": [
+        "stm32l0",
+        "stm32l0x2",
+        "stm32"
+    ],
+    "cflags": [
+        "--target=armv6m-none-eabi",
+        "-Qunused-arguments"
+    ],
+    "extra-files": [
+        "src/device/stm32/stm32l0x2.s"
+    ]
+}