drm/i915: Move crtc_state to tighter scope

intel_modeset_setup_hw_state() doesn't need the crtc_state at the
top level scope. Move it to where it's needed.

Reviewed-by: Manasi Navare <manasi.d.navare@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191118164430.27265-5-ville.syrjala@linux.intel.com