drm/i915/soc: stop using IS_GEN9_LP() and IS_GEN9_BC()

Replace IS_GEN9_LP() and IS_GEN9_BC() with direct platform checks. This
lets us remove their compat counterparts, as neither soc/ nor /display
now no longer needs them.

v2: Use !A && !B instead of !(A || B) (Ville)

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com> # v1
Link: https://patchwork.freedesktop.org/patch/msgid/20240930124056.3541988-2-jani.nikula@intel.com


Signed-off-by: Jani Nikula <jani.nikula@intel.com>