ext4: remove unused ext4_{set}/{clear}_bit_atomic

Remove ext4_set_bit_atomic and ext4_clear_bit_atomic which are defined but not
used.

Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Link: https://lore.kernel.org/r/20230801143204.2284343-8-shikemeng@huaweicloud.com


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