btrfs: remove btrfs_lru_cache_is_full() inline function

It's not used anywhere at the moment, but it was used in earlier version
of a patch that removed its use in the second version. So just remove
btrfs_lru_cache_is_full().
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/lru_cache.h

@@ -55,11 +55,6 @@ static inline unsigned int btrfs_lru_cache_size(const struct btrfs_lru_cache *ca
 	return cache->size;
 }
 
-static inline bool btrfs_lru_cache_is_full(const struct btrfs_lru_cache *cache)
-{
-	return cache->size >= cache->max_size;
-}
-
 static inline struct btrfs_lru_cache_entry *btrfs_lru_cache_lru_entry(
 					      struct btrfs_lru_cache *cache)
 {