drm/i915/wm: Use drm_get_format_info() in SKL+ cursor DDB allocation

drm/i915/wm: Use drm_get_format_info() in SKL+ cursor DDB allocation

Replace the technically inaccurate drm_format_info() with the
accurate drm_get_format_info() in the SKL+ cursor DDB
allocation code.

Since we're only interested in the linear modifier here, the two
functions do actually return the same information. But let's not
use drm_format_info() to avoid setting a bad example.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patch.msgid.link/20251107181126.5743-7-ville.syrjala@linux.intel.com
Reviewed-by: Jani Nikula <jani.nikula@intel.com>