drm/i915: use PIPE_CONF_CHECK_BOOL() for bool members

Don't treat bools as integers.

v2: Rebase

Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231129173317.1192269-1-jani.nikula@intel.com