drm/i915: Simplify intel_crtc_copy_uapi_to_hw_state_nomodeset()

Rewrite intel_crtc_copy_uapi_to_hw_state_nomodeset() in a
slightly more straightforward manner.

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/20211022103304.24164-6-ville.syrjala@linux.intel.com