lightnvm: Make functions not used by ouside static

Mark functions not used by ouside of thier implementing file as static.

Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Matias Bjørling <m@bjorling.me>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/drivers/lightnvm/core.c b/drivers/lightnvm/core.c
index 13993c9..8beb9c0 100644
--- a/drivers/lightnvm/core.c
+++ b/drivers/lightnvm/core.c
@@ -110,7 +110,7 @@
 	return NULL;
 }
 
-struct nvmm_type *nvm_init_mgr(struct nvm_dev *dev)
+static struct nvmm_type *nvm_init_mgr(struct nvm_dev *dev)
 {
 	struct nvmm_type *mt;
 	int ret;