[bugfix][T108][bug-view-2468] solve the problem of mbtk_ril_open interface leakage fd

Only Configure: No
Affected branch: YUNDONG_BASE1.0
Affected module: dm
Self-test: yes
Doc Update: no

Change-Id: I37a1241668d4eb8564042a95894370f863657977
diff --git a/mbtk/libmbtk_lib/ril/v2/mbtk_ril_api.c b/mbtk/libmbtk_lib/ril/v2/mbtk_ril_api.c
index 3087c68..7d6218e 100755
--- a/mbtk/libmbtk_lib/ril/v2/mbtk_ril_api.c
+++ b/mbtk/libmbtk_lib/ril/v2/mbtk_ril_api.c
@@ -468,6 +468,7 @@
     }
 
 read_thread_exit:
+    close(epoll_fd);
     LOGD("info_read thread exit.");
     return NULL;
 }