Fix compilation with RC_Channels not available #34085

Job	Run time
build (stm32f7, chibios, 10)	4m 5s
build (stm32h7, chibios, 10)	3m 22s
build (fmuv2-plane, chibios, 10)	1m 45s
build (periph-build, chibios, 10)	5m 12s
build (iofirmware, chibios, 10)	1m 22s
build (CubeOrange-bootloader, chibios, 10)	1m 2s
build (fmuv3-bootloader, chibios, 10)	57s
build (revo-bootloader, chibios, 10)	50s
build (stm32h7-debug, chibios, 10)	2m 4s
build (fmuv3, chibios, 10)	4m 46s
build (revo-mini, chibios, 10)	4m 42s
build (MatekF405-Wing, chibios, 10)	4m 10s
build (CubeOrange-ODID, chibios, 10)	2m 50s
build (CubeRedPrimary-bootloader, chibios, 10)	1m 3s
build (configure-all, chibios, 10)	8m 42s
build (build-options-defaults-test, chibios, 10)	6m 10s
build (signing, chibios, 10)	3m 8s
	56m 10s

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