ext4: remove unneeded NULL check of buffer_head in ext4_mark_inode_used()

If gdp from ext4_get_group_desc() is not NULL, then returned group_desc_bh
won't be NULL either. Remove check of group_desc_bh and only check
returned gdp from ext4_get_group_desc() like how other callers do.

Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Link: https://patch.msgid.link/20240820132234.2759926-7-shikemeng@huaweicloud.com


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