ext4: remove useless local variable 'blocksize'

Since sb->s_blocksize is now initialized at the very beginning, the
local variable 'blocksize' in __ext4_fill_super() is not needed now.
Remove it and use sb->s_blocksize instead.

Signed-off-by: Jason Yan <yanaijie@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20220916141527.1012715-16-yanaijie@huawei.com


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