Fix for 3GPP issue 1749: Use of divide1616 and idivide1616 with constant denominator

Link #1749

This MR holds changes regarding idiv1616 in 2 ways:

1. If denominator is constant and power of 2 then Right shift( shr ) is done instead of idiv1616.
2. If denominator is constant and not a power of 2 then, multiplication( mult ) is done with inverse of denominator instead of idiv1616

The changes are done only in IVAS functions.