nir: Unroll loops with multiplication and left shift incrementation

Calculate number of iterations for loops, where incrementation is done
by multiplication.

Multiplication by  power of two may  be transformed to left  shift for
integers, thereof requires separate algorithm.

Signed-off-by: Yevhenii Kolesnikov <yevhenii.kolesnikov@globallogic.com>
22 jobs for !17 with opt_loop-unroll-mult in 21 minutes and 24 seconds (queued for 3 seconds)
merge request