GCS_MAVLink: correct a debugging message #39967

Job	Run time
build (stm32f7, chibios, 10)	6m 18s
build (stm32h7, chibios, 10)	5m 50s
build (fmuv2-plane, chibios, 10)	4m 15s
build (periph-build, chibios, 10)	5m 35s
build (iofirmware, chibios, 10)	3m 37s
build (CubeOrange-bootloader, chibios, 10)	2m 59s
build (fmuv3-bootloader, chibios, 10)	3m 13s
build (revo-bootloader, chibios, 10)	3m 13s
build (stm32h7-debug, chibios, 10)	9m 25s
build (fmuv3, chibios, 10)	7m 54s
build (revo-mini, chibios, 10)	6m 20s
build (MatekF405-Wing, chibios, 10)	6m 53s
build (CubeOrange-ODID, chibios, 10)	4m 38s
build (CubeRedPrimary-bootloader, chibios, 10)	3m 14s
build (configure-all, chibios, 10)	12m 27s
build (build-options-defaults-test, chibios, 10)	9m 30s
build (signing, chibios, 10)	5m 4s
build (CubeOrange-PPP, chibios, 10)	4m 29s
build (SOHW, chibios, 10)	5m 34s
build (Pixhawk6X-PPPGW, chibios, 10)	3m 23s
build (new-check, chibios, 10)	6m 40s
	2h 0m 31s

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