exofs/ore.c: local functions should be static

This quiets the sparse noise:

warning: symbol '_calc_trunk_info' was not declared. Should it be static?
Signed-off-by: NH Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: NBoaz Harrosh <bharrosh@panasas.com>

fs/exofs/ore.c

@@ -753,8 +753,8 @@ struct _trunc_info {
 	unsigned max_devs;
 };
 
-void _calc_trunk_info(struct ore_layout *layout, u64 file_offset,
-		       struct _trunc_info *ti)
+static void _calc_trunk_info(struct ore_layout *layout, u64 file_offset,
+			     struct _trunc_info *ti)
 {
 	unsigned stripe_unit = layout->stripe_unit;