scoutfs: Tidy some enum usage

Prefer named to anonymous enums. This helps readability a little.

Use enum as param type if possible (a couple spots).

Remove unused enum in lock_server.c.

Define enum spbm_flags using shift notation for consistency.

Rename get_file_block()'s "gfb" parameter to "flags" for consistency.

Signed-off-by: Andy Grover <agrover@versity.com>

kmod/src/item.c

@@ -715,7 +715,7 @@ static void move_page_items(struct super_block *sb,
 	}
 }
 
-enum {
+enum page_intersection_type {
 	PGI_DISJOINT,
 	PGI_INSIDE,
 	PGI_START_OLAP,