Fix bad flush #33

Job	Run time
build-board (device/audio_test device/board_test device/cdc_dual_ports device/cdc_msc)	20s
build-arm (broadcom_32bit)	46s
build-board (device/cdc_msc_freertos device/dfu_runtime device/hid_composite device/hid_composite...	22s
build-arm (imxrt)	3m 43s
build-board (device/hid_generic_inout device/hid_multiple_interface device/midi_test device/msc_d...	17s
unit-test	39s
build-arm (lpc15)	43s
build-arm (lpc18)	1m 21s
build-board (device/net_lwip_webserver)	19s
build-arm (lpc54)	1m 26s
build-board (device/uac2_headset device/usbtmc device/webusb_serial host/cdc_msc_hid)	24s
build-arm (lpc55)	2m 24s
build-arm (mm32)	1m 2s
build-arm (msp432e4)	1m 0s
build-arm (nrf)	4m 45s
build-arm (rp2040)	6m 3s
build-arm (samd11)	1m 42s
build-arm (samd21)	9m 34s
build-arm (samd51)	10m 0s
build-arm (saml2x)	7m 7s
build-arm (stm32f0)	2m 1s
build-arm (stm32f1)	1m 16s
build-arm (stm32f4)	4m 11s
build-arm (stm32f7)	3m 27s
build-arm (stm32h7)	2m 55s
build-arm (stm32l4)	2m 6s
build-arm (tm4c123)	52s
build-arm (xmc4000)	47s
	1h 11m 32s

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