hv: hv_balloon: remove duplicated include from hv_balloon.c

Remove duplicated include.
Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Acked-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/hv/hv_balloon.c

@@ -29,7 +29,6 @@
 #include <linux/memory_hotplug.h>
 #include <linux/memory.h>
 #include <linux/notifier.h>
-#include <linux/mman.h>
 #include <linux/percpu_counter.h>
 
 #include <linux/hyperv.h>