Btrfs: kick out redundant stuff in convert_extent_bit

clear_state_bit will do merge_state for us, so kick out the redundant one.
Signed-off-by: Liu Bo <liubo2009@cn.fujitsu.com>

fs/btrfs/extent_io.c

@@ -966,8 +966,6 @@ int convert_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 
 		set_state_bits(tree, state, &bits);
 		clear_state_bit(tree, state, &clear_bits, 0);
-
-		merge_state(tree, state);
 		if (last_end == (u64)-1)
 			goto out;
 
@@ -1012,7 +1010,6 @@ int convert_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 		if (state->end <= end) {
 			set_state_bits(tree, state, &bits);
 			clear_state_bit(tree, state, &clear_bits, 0);
-			merge_state(tree, state);
 			if (last_end == (u64)-1)
 				goto out;
 			start = last_end + 1;
@@ -1073,8 +1070,6 @@ int convert_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 
 		set_state_bits(tree, prealloc, &bits);
 		clear_state_bit(tree, prealloc, &clear_bits, 0);
-
-		merge_state(tree, prealloc);
 		prealloc = NULL;
 		goto out;
 	}