!27 [stm32] fix linkscript issue in stm32f411-atk-nano

Merge pull request !27 from RT-Thread/gitee_fix

bsp/stm32/stm32f411-atk-nano/board/linker_scripts/link.lds

@@ -6,8 +6,8 @@
 /* Program Entry, set to mark it as "used" and avoid gc */
 MEMORY
 {
-    ROM (rx) : ORIGIN = 0x08000000, LENGTH = 256 /* 256KB flash */
-    RAM (rw) : ORIGIN = 0x20000000, LENGTH =  128k /* 128K sram */
+    ROM (rx) : ORIGIN = 0x08000000, LENGTH = 256k /* 256KB flash */
+    RAM (rw) : ORIGIN = 0x20000000, LENGTH = 128k /* 128K sram */
 }
 ENTRY(Reset_Handler)
 _system_stack_size = 0x200;