ACPI: DPTF: Add new PCH FIVR methods

Some additional information is required for updating PCH FIVR values
upon WiFi channel changes.

New attributes added to the existing sysfs:

fivr_switching_freq_mhz	: Get the FIVR switching control frequency.
			  Uses ACPI method GFCS.

fivr_switching_fault_status: Read the FIVR switching frequency control
			     fault status. Uses ACPI method GFFS.

ssc_clock_info : Presents SSC (spread spectrum clock) information for
		 EMI (Electro magnetic interference) control. Use ACPI
		 method GEMI (refer to the description of GEMI method
		 below).

GFFS
This ACPI method is used to read the FIVR switching frequency control
fault status.
Bits	Description
[0:0]	Fault status when set to 1
[31:1]	Reserved

GFCS
This ACPI method is used to read the FIVR switching control frequency.
Bits	Description
[11:0]	Actual Frequency = value * XTAL_FREQ / 128
[31:12]	Reserved

GEMI
This ACPI method is used to read the programmed register value for
EMI (Electro magnetic interference) control.

Bits	Description
[7:0]	Sets clock spectrum spread percentage:
	0x00=0.2% , 0x3F=10%
	1 LSB = 0.1% increase in spread (for
	settings 0x01 thru 0x1C)
	1 LSB = 0.2% increase in spread (for
	settings 0x1E thru 0x3F)
[8]	When set to 1, enables spread
	spectrum clock
[9]	0: Triangle mode. FFC frequency
	walks around the Fcenter in a linear
	fashion
	1: Random walk mode. FFC frequency
	changes randomly within the SSC
	(Spread spectrum clock) range
[10]	0: No white noise. 1: Add white noise
	to spread waveform
[11]	When 1, future writes are ignored.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>