İ don't think one can deduce ps4 clock speed from this it can be many factors:
1. CPU cores reserved for OS
2. Memory interface
3. Status of API and drivers
4. Effect of gpu on test, how do we know this is purely a CPU test?
They've been pretty vocal that all multiplatform titles will look and run better on the PS4. The only reason MS announced the XB1 CPU clocks was due to the drumming they were taking on comparison specs. Otherwise, we likely never would have heard the One's CPU speed either.
GPUs are a lot more important in consoles than CPUs. You can't compare a console to a phone or even a PC anyway. Different architecture, RAM, bandwidth, no bottleneck, no API overhead, closed system... You can squeeze a lot more power from a console.
Games are running more and more through the GPU these days. Everyone claiming that it's a mobile part is referring to a 4 core version. Both consoles have 8 cores. The CPU are sufficient for what needs to be done, nothing more. It's a big part of why PS4 is heavily customized for GPU compute functionality. You'll be able to do more both in compute and visuals with a heavier GPU these days than you will with a beefy CPU.