drm/i915/mtl: Modify CAGF functions for MTL

Update CAGF functions for MTL to get actual resolved frequency of 3D and
SAMedia.

v2: Update MTL_MIRROR_TARGET_WP1 position/formatting (MattR)
    Move MTL branches in cagf functions to top (MattR)
    Fix commit message (Andi)
v3: Added comment about registers not needing forcewake for Gen12+ and
    returning 0 freq in RC6
v4: Use REG_FIELD_GET and uncore (Rodrigo)

Bspec: 66300

Signed-off-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Signed-off-by: Badal Nilawar <badal.nilawar@intel.com>
Reviewed-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Acked-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221114123348.3474216-4-badal.nilawar@intel.com