ext4: remove redundant assignment to variable split_flag1

Variable split_flag1 is being assigned a value that is never read,
it is being re-assigned a new value in the following code block.
The assignment is redundant and can be removed.

Cleans up clang scan build warning:
fs/ext4/extents.c:3371:2: warning: Value stored to 'split_flag1' is
never read [deadcode.DeadStores]
Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Link: https://lore.kernel.org/r/20220301121644.997833-1-colin.i.king@gmail.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/extents.c

@@ -3368,7 +3368,6 @@ static int ext4_split_extent(handle_t *handle,
 		return -EFSCORRUPTED;
 	}
 	unwritten = ext4_ext_is_unwritten(ex);
-	split_flag1 = 0;
 
 	if (map->m_lblk >= ee_block) {
 		split_flag1 = split_flag & EXT4_EXT_DATA_VALID2;