platform/x86/amd/pmf: Add util layer and userspace character device interface

Add a util layer to AMD PMF that exposes a minimal userspace interface
via a character device for metrics monitoring and feature discovery.

This creates /dev/amdpmf_interface with basic ioctl support to retrieve
PMF metrics such as:
*  Power source and power slider position
*  Platform type, lid state, and user presence
*  Skin temperature and ambient light
*  BIOS input parameters (1-10)
*  Graphics workload metrics
*  CPU C-state residency (average and maximum)
*  Socket power consumption
*  Auto Mode: Automatic power profile switching based on system activity
*  Static Power Slider: User-selectable power profiles
*  Policy Builder (Smart PC): Action based policy management
*  Dynamic Power Slider AC: Adaptive power profiles when on AC power
*  Dynamic Power Slider DC: Adaptive power profiles when on battery

The interface enables smoother integration with userspace tools such as
AMD SystemDeck [1], which is widely used for monitoring and controlling
power and thermal behavior on AMD platforms. These tools help designers
keep major components within thermal limits to ensure proper operation
and enhance overall system stability and reliability.

The feature is gated behind the CONFIG_AMD_PMF_UTIL_SUPPORT Kconfig
option, allowing it to be disabled if not needed. The implementation
uses existing PMF infrastructure to populate data from the TA (Trusted
Application) shared memory buffer.

Link: https://docs.amd.com/v/u/en-US/68773_0.50 [1]

Co-developed-by: Sanket Goswami <Sanket.Goswami@amd.com>
Signed-off-by: Sanket Goswami <Sanket.Goswami@amd.com>
Signed-off-by: Shyam Sundar S K <Shyam-sundar.S-k@amd.com>
Link: https://patch.msgid.link/20260609081044.2416731-2-Shyam-sundar.S-k@amd.com
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

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