SITL: Change division to multiplication #1082

Job	Run time
build (stm32f7, chibios, 10)	14m 37s
build (stm32h7, chibios, 10)	14m 3s
build (fmuv2-plane, chibios, 10)	7m 23s
build (periph-build, chibios, 10)	13m 38s
build (iofirmware, chibios, 10)	4m 22s
build (CubeOrange-bootloader, chibios, 10)	3m 13s
build (fmuv3-bootloader, chibios, 10)	3m 11s
build (revo-bootloader, chibios, 10)	3m 17s
build (stm32h7-debug, chibios, 10)	8m 42s
build (fmuv3, chibios, 10)	14m 50s
build (revo-mini, chibios, 10)	11m 50s
build (MatekF405-Wing, chibios, 10)	12m 28s
build (CubeOrange-ODID, chibios, 10)	9m 51s
build (CubeRedPrimary-bootloader, chibios, 10)	3m 13s
build (configure-all, chibios, 10)	12m 48s
build (build-options-defaults-test, chibios, 10)	24m 8s
build (signing, chibios, 10)	11m 11s
build (CubeOrange-PPP, chibios, 10)	8m 26s
build (CubeRed-EKF2, chibios, 10)	8m 18s
build (SOHW, chibios, 10)	13m 58s
build (Pixhawk6X-PPPGW, chibios, 10)	4m 51s
build (new-check, chibios, 10)	14m 41s
	3h 42m 59s

Provide feedback