For MTL, when reading from HW, RP0, RP1 (actuall RPe) and RPn freq use an
entirely different set of registers with different fields, bitwidths and
units.

v2: Move MTL check into a separate function (Jani)

Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Badal Nilawar <badal.nilawar@intel.com>
Signed-off-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220910143844.1755324-4-ashutosh.dixit@intel.com