ext4: remove unnecessary goto in ext4_mb_mark_diskspace_used

When ext4_read_block_bitmap fails, we can return PTR_ERR(bitmap_bh) to
remove unnecessary NULL check of bitmap_bh.

Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Link: https://lore.kernel.org/r/20230303172120.3800725-18-shikemeng@huaweicloud.com


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