Include lr in delay_ns clobber list

Author: mcbridejc

src/modm/platform/core/cortex/delay_impl.hpp.in

@@ -43,7 +43,7 @@ void delay_ns(uint32_t ns)
     asm volatile(
         "mov r0, %0 \n\t"
         "blx %1"
-        :: "r" (ns), "l" (platform::delay_ns) : "r0", "r1", "r2");
+        :: "r" (ns), "l" (platform::delay_ns) : "r0", "r1", "r2", "lr");
 }