Expose Intel RPS threshold_up and threshold_down values

At the moment intel_rps.c has set the threshold_up and threshold_down values to 95 and 85 respectively in the rps_set_power function, we would like to be able to modify these values on the fly preferably through sysfs nodes under certain conditions, similar to how we can modify other parameters like the cpu_min/max_scaling_freq

For our use case we wish to change these values when the device is plugged-in and inside GameMode(and switch back to the default values when either of these conditions is not met) in order to enhance the performance of games. Please see the data attached below for more information about how it affects performance, the FPS(50/70) column represents the tweaked threshold_down and threshold_up values:

Game	API	FPS(85/95)	FPS(50/70)	Perf Delta %
CS:GO	GL	96.12	112.42	14.50
CS:GO	Vulkan	93.64	107.54	12.93
Civ6	GL	27.88	31.32	10.98
Strange Brigade	DX12	37	37	0.00