drm/i915: Remove runtime suspended boolean from intel_runtime_pm struct

It's not necessary to carry separate suspended status information in
intel_runtime_pm struct as this information is already in underlying device
structure. Remove it and use pm_runtime_suspended() to obtain suspended
status information when needed.

Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Imre Deak <imre.deak@intel.com>

Signed-off-by: Jouni Högander <jouni.hogander@intel.com>
Acked-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230913100430.3433969-1-jouni.hogander@intel.com