ext4: get block from bh in ext4_free_blocks for fast commit replay

ext4_free_blocks will retrieve block from bh if block parameter is zero.
Retrieve block before ext4_free_blocks_simple to avoid potentially
passing wrong block to ext4_free_blocks_simple.

Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: stable@kernel.org
Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Link: https://lore.kernel.org/r/20230603150327.3596033-9-shikemeng@huaweicloud.com


Signed-off-by: Theodore Ts'o <tytso@mit.edu>