All callers of flush_space pass the same number for orig/num_bytes
arguments. Let's remove one of the numbers and also modify the trace
point to show only a single number - bytes requested.
Seems that last point where the two parameters were treated differently
is before the ticketed enospc rework.
Signed-off-by: Nikolay Borisov <nborisov@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>