Use i915 HWMON to display/modify dGfx power PL1 limit and TDP setting.

v2:
  - Fix review comments (Ashutosh)
  - Do not restore power1_max upon module unload/load sequence
    because on production systems modules are always loaded
    and not unloaded/reloaded (Ashutosh)
  - Fix review comments (Jani)
  - Remove endianness conversion (Ashutosh)
v3: Add power1_rated_max (Ashutosh)
v4:
  - Use macro HWMON_CHANNEL_INFO to define power channel (Guenter)
  - Update the date and kernel version in Documentation (Badal)
v5: Use hwm_ prefix for static functions (Ashutosh)
v6: Fix review comments (Ashutosh)
v7:
  - Define PCU_PACKAGE_POWER_SKU for DG1,DG2 and move
    PKG_PKG_TDP to intel_mchbar_regs.h (Anshuman)
  - KernelVersion: 6.2, Date: February 2023 in doc (Tvrtko)
v8: Change contact to intel-gfx (Rodrigo)
    Minor change to val_sku_unit init (Andi)

Cc: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Dale B Stimson <dale.b.stimson@intel.com>
Signed-off-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Signed-off-by: Riana Tauro <riana.tauro@intel.com>
Signed-off-by: Badal Nilawar <badal.nilawar@intel.com>
Acked-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Reviewed-by: Anshuman Gupta <anshuman.gupta@intel.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Signed-off-by: Anshuman Gupta <anshuman.gupta@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221013154526.2105579-4-ashutosh.dixit@intel.com