hwdef:free flash for space critical bds #1334

Job	Run time
build (stm32f7, chibios, 10)	5m 9s
build (stm32h7, chibios, 10)	5m 36s
build (fmuv2-plane, chibios, 10)	2m 42s
build (periph-build, chibios, 10)	8m 30s
build (iofirmware, chibios, 10)	1m 56s
build (CubeOrange-bootloader, chibios, 10)	1m 29s
build (fmuv3-bootloader, chibios, 10)	1m 0s
build (revo-bootloader, chibios, 10)	1m 3s
build (stm32h7-debug, chibios, 10)	3m 34s
build (fmuv3, chibios, 10)	7m 30s
build (revo-mini, chibios, 10)	5m 37s
build (MatekF405-Wing, chibios, 10)	8m 7s
build (CubeOrange-ODID, chibios, 10)	4m 32s
build (CubeRedPrimary-bootloader, chibios, 10)	1m 3s
build (configure-all, chibios, 10)	9m 47s
build (build-options-defaults-test, chibios, 10)	8m 52s
build (signing, chibios, 10)	3m 30s
	1h 19m 57s

Provide feedback