ext4: remove unnecessary initialization of count2 in set_flexbg_block_bitmap

We always overwrite count2 to "EXT4_CLUSTERS_PER_GROUP(sb) -
(first_cluster - start)" after its initialization in for loop
initialization statement .
Just remove unnecessary initialization of count2.

Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Theodore Ts'o <tytso@mit.edu>
Link: https://lore.kernel.org/r/20230826174712.4059355-14-shikemeng@huaweicloud.com


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