jbd2: remove repeated assignments in __jbd2_log_wait_for_space()

At the beginning, nblocks has been assigned. There is no need
to repeat the assignment in the while loop, and remove it.

Signed-off-by: Liu Song <[e-mail]>
Signed-off-by: Theodore Ts'o <[e-mail]>
Reviewed-by: Jan Kara <[e-mail]>

fs/jbd2/checkpoint.c

···
 			return;
 		}
 		spin_lock(&journal->j_list_lock);
-		nblocks = jbd2_space_needed(journal);
 		space_left = jbd2_log_space_left(journal);
 		if (space_left < nblocks) {
 			int chkpt = journal->j_checkpoint_transactions != NULL;