x86: chromebox_panther: Drop the cache line size hack

Now that the RTL8169 driver warning is fixed we can drop this.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

include/configs/chromebox_panther.h

@@ -11,7 +11,5 @@
 #include <configs/x86-chromebook.h>
 
 #define CONFIG_RTL8169
-/* Avoid a warning in the Realtek Ethernet driver */
-#define CONFIG_SYS_CACHELINE_SIZE 16
 
 #endif	/* __CONFIG_H */