thermal: intel: int340x: Add DLVR support for RFIM control

Add support for DLVR (Digital Linear Voltage Regulator) attributes,
which can be used to control RFIM.

Here instead of "fivr" another directory "dlvr" is created with DLVR
attributes:

/sys/bus/pci/devices/0000:00:04.0/dlvr
├── dlvr_freq_mhz
├── dlvr_freq_select
├── dlvr_hardware_rev
├── dlvr_pll_busy
├── dlvr_rfim_enable
└── dlvr_spread_spectrum_pct
└── dlvr_control_mode
└── dlvr_control_lock

Attributes
dlvr_freq_mhz (RO):
Current DLVR PLL frequency in MHz.

dlvr_freq_select (RW):
Sets DLVR PLL clock frequency.

dlvr_hardware_rev (RO):
DLVR hardware revision.

dlvr_pll_busy (RO):
PLL can't accept frequency change when set.

dlvr_rfim_enable (RW):
0: Disable RF frequency hopping, 1: Enable RF frequency hopping.

dlvr_control_mode (RW):
Specifies how frequencies are spread. 0: Down spread, 1: Spread in Center.

dlvr_control_lock (RW):
1: future writes are ignored.

dlvr_spread_spectrum_pct (RW)
A write to this register updates the DLVR spread spectrum percent value.

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