Improve reporting of layout for raid10.

Improve reporting of layout for raid10.

Showing e.g.

   near=1, far=2

for the 'far2' layout of raid10 is confusing even though there is a
sense in which is it correct.

Make it less confusing by only printing whichever number is not 1.
If both are 1, make that clear too (i.e. no redundancy).