Slightly simplify is_significantly_above_a_power_of_2() to make it
easier to understand:
* Remove the explicit negative answer for x <= 4. The only functional
difference this makes is that is_significantly_above_a_power_of_2(3)
is now true.
* Shift the most significant bit of x to position 8 rather than 15.
This makes the final comparison easier to explain.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
3b05615e5b