Add missing rc.sysinit file in the ROMFS #35

Job	Run time
build (check_format)	1m 3s
build (check_newlines)	1m 27s
build (tests)	5m 47s
build (tests_coverage)	7m 25s
build (px4_fmu-v2_default stack_check)	3m 11s
build (validate_module_configs)	46s
build (shellcheck_all)	1m 37s
build (NO_NINJA_BUILD=1 px4_fmu-v5_default)	4m 5s
build (NO_NINJA_BUILD=1 px4_sitl_default)	3m 18s
build (px4_sitl_allyes)	4m 26s
build (airframe_metadata)	59s
build (module_documentation)	58s
build (parameters_metadata)	1m 4s
	36m 6s

Provide feedback