batman-adv: Add missing include for EPOLL* constants

Fixes: a9a08845e9ac ("vfs: do bulk POLL* -> EPOLL* replacement")
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
diff --git a/net/batman-adv/icmp_socket.c b/net/batman-adv/icmp_socket.c
index e91f29c..5daa3d5 100644
--- a/net/batman-adv/icmp_socket.c
+++ b/net/batman-adv/icmp_socket.c
@@ -24,6 +24,7 @@
 #include <linux/debugfs.h>
 #include <linux/errno.h>
 #include <linux/etherdevice.h>
+#include <linux/eventpoll.h>
 #include <linux/export.h>
 #include <linux/fcntl.h>
 #include <linux/fs.h>