clk: sunxi: clean the magic number of mux parents
clk: sunxi: clean the magic number of mux parents

This was pointed out during the review of the factor patches. Let's
indicate what does that magic 5 mean.

Signed-off-by: Emilio López <86fa523305b8ad6a8a853c04cfef24a0445908d3@elopez.com.ar>
Acked-by: Mike Turquette <6dab61939fc5e23761050a66932f032dceda5ebf@linaro.org>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs