ext4: correct the left/middle/right debug message for binsearch

The debuginfo for binsearch want to show the left/middle/right extent
while the process search for the goal block. However we show this info
after we change right or left.

Link: https://lore.kernel.org/r/20210903062748.4118886-2-yangerkun@huawei.com


Signed-off-by: yangerkun <yangerkun@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>