Suck the "do we have iboost?" platform checks into a small helper.

Cc: Imre Deak <imre.deak@intel.com>
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211001130107.1746-2-ville.syrjala@linux.intel.comReviewed-by: NImre Deak <imre.deak@intel.com>