Compile firmware for STM32F072x8 instead of xB

Since the firmware is under 32 KiB, I figured there's not much reason to
use a microcontroller with 128 KiB of flash.  The new boards use
STM32F072x8 chips, which only have 64 KiB of flash.  This allows for the
firmware to grow, while not being quite so ridiculous as before.

This commit sets the Makefile to put the configuration at the end of the
64 KiB flash chip, and to use a new linker script for the same chip.

Makefile

 include $(CHIBIOS)/test/rt/test.mk
 
 # Define linker script file here
-LDSCRIPT=$(CHIBIOS)/../ld/STM32F072xB.ld
+LDSCRIPT=$(CHIBIOS)/../ld/STM32F072x8.ld
 
 # C sources that can be compiled in ARM or THUMB mode depending on the global
 # setting.
 #
 
 # List all user C define here, like -D_DEBUG=1
-UDEFS = -DPDB_CONFIG_BASE=0x0801F800
+UDEFS = -DPDB_CONFIG_BASE=0x0800F800
 
 # Define ASM defines here
 UADEFS =

ld/STM32F072x8.ld

+/*
+    ChibiOS - Copyright (C) 2006..2015 Giovanni Di Sirio
+
+    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.
+*/
+
+/*
+ * STM32F072x8 memory setup.
+ *
+ * Flash is defined as 2k smaller than it really is to reserve the last page
+ * for configuration.
+ */
+MEMORY
+{
+    flash : org = 0x08000000, len = 62k
+    ram0  : org = 0x20000000, len = 16k
+    ram1  : org = 0x00000000, len = 0
+    ram2  : org = 0x00000000, len = 0
+    ram3  : org = 0x00000000, len = 0
+    ram4  : org = 0x00000000, len = 0
+    ram5  : org = 0x00000000, len = 0
+    ram6  : org = 0x00000000, len = 0
+    ram7  : org = 0x00000000, len = 0
+}
+
+/* RAM region to be used for Main stack. This stack accommodates the processing
+   of all exceptions and interrupts*/
+REGION_ALIAS("MAIN_STACK_RAM", ram0);
+
+/* RAM region to be used for the process stack. This is the stack used by
+   the main() function.*/
+REGION_ALIAS("PROCESS_STACK_RAM", ram0);
+
+/* RAM region to be used for data segment.*/
+REGION_ALIAS("DATA_RAM", ram0);
+
+/* RAM region to be used for BSS segment.*/
+REGION_ALIAS("BSS_RAM", ram0);
+
+/* RAM region to be used for the default heap.*/
+REGION_ALIAS("HEAP_RAM", ram0);
+
+INCLUDE rules.ld