stm32f1x_cl: Add initial support for STM32F1x connectivity line

This currently supports the stm32f107, but support will be added for
the F105 shortly (missing a linker script and I can't properly test
without a devkit).

cpu/arm/stm32f1x_cl/rtimer-arch.h

@@ -0,0 +1,22 @@
+/**
+ * \file
+ *         Header file for the STM32F107-specific rtimer code
+ * \author
+ *         Jeff Ciesielski <jeffciesielski@gmail.com>
+ * Adapted from stm32f103 example
+ */
+
+#ifndef __RTIMER_ARCH_H__
+#define __RTIMER_ARCH_H__
+
+#include "sys/rtimer.h"
+
+#define RTIMER_ARCH_SECOND (MCK/1024)
+
+void rtimer_arch_init(void);
+
+void rtimer_arch_set(rtimer_clock_t t);
+
+rtimer_clock_t rtimer_arch_now(void);
+
+#endif /* __RTIMER_ARCH_H__ */