drm/i915/crtc: move crtc initialization loop to intel_crtc.c

drm/i915/crtc: move crtc initialization loop to intel_crtc.c

intel_display_driver_probe_nogem() is too high of an abstraction level
to be looping and initializing individual CRTCs. Move this to
intel_crtc.c and repurpose intel_crtc_init() to initialize all
CRTCs. Make the original a static __intel_crtc_init() for initializing a
single CRTC.

Reviewed-by: Chaitanya Kumar Borah <chaitanya.kumar.borah@intel.com>
Link: https://patch.msgid.link/20251204143235.3138973-1-jani.nikula@intel.com
Signed-off-by: Jani Nikula <jani.nikula@intel.com>