[bsp][efm32] 增加RT_LIBC_USING_TIME

bsp/efm32/rtconfig.h

@@ -213,6 +213,7 @@
 /* SECTION: Runtime library */
 // #define RT_USING_NOLIBC
 // #define RT_USING_NEWLIB
+#define RT_LIBC_USING_TIME
 
 /* SECTION: Console options */
 #define RT_USING_CONSOLE