btrfs: remove superfluous BUG_ON() in integrity checks

btrfsic_process_superblock() BUG_ON()s if 'state' is NULL. But this can
never happen as the only caller from btrfsic_process_superblock() is
btrfsic_mount() which allocates 'state' some lines above calling
btrfsic_process_superblock() and checks for the allocation to succeed.

Let's just remove the impossible to hit BUG_ON().
Signed-off-by: Johannes Thumshirn <jth@kernel.org>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/check-integrity.c

@@ -636,7 +636,6 @@ static int btrfsic_process_superblock(struct btrfsic_state *state,
 	int ret = 0;
 	int pass;
 
-	BUG_ON(NULL == state);
 	selected_super = kzalloc(sizeof(*selected_super), GFP_NOFS);
 	if (NULL == selected_super) {
 		pr_info("btrfsic: error, kmalloc failed!\n");