ext4: Remove unnecessary release when memory allocation failed in ext4_mb_init_cache

If we alloc array of buffer_head failed, there is no resource need to be
freed and we can simpily return error.

Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Link: https://lore.kernel.org/r/20230303172120.3800725-10-shikemeng@huaweicloud.com


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