makefiles/features_modules: do not generate init for ESP RTT
makefiles/features_modules: do not generate init for ESP RTT

This avoids the generation of the unneeded modules
periph_init_rtt_hw_rtc and periph_init_rtt_hw_sys.

OlegHahm/RIOT,ant9000/RIOT,ant9000/RIOT,ant9000/RIOT,kYc0o/RIOT,kaspar030/RIOT,ant9000/RIOT,ant9000/RIOT,jasonatran/RIOT,jasonatran/RIOT,RIOT-OS/RIOT,kYc0o/RIOT,miri64/RIOT,RIOT-OS/RIOT,miri64/RIOT,kYc0o/RIOT,OlegHahm/RIOT,miri64/RIOT,OlegHahm/RIOT,jasonatran/RIOT,miri64/RIOT,RIOT-OS/RIOT,miri64/RIOT,jasonatran/RIOT,kaspar030/RIOT,OlegHahm/RIOT,kYc0o/RIOT,OlegHahm/RIOT,kYc0o/RIOT,kaspar030/RIOT,kaspar030/RIOT,kaspar030/RIOT,jasonatran/RIOT,RIOT-OS/RIOT,RIOT-OS/RIOT