GR716: implement flash driver #990

Job	Run time
call-ci / build (armv7a7-imx6ull-evk)	1m 32s
call-ci / build (armv7a9-zynq7000-qemu)	1m 44s
call-ci / build (armv7a9-zynq7000-zedboard)	1m 17s
call-ci / build (armv7a9-zynq7000-zturn)	1m 39s
call-ci / build (armv7m4-stm32l4x6-nucleo)	1m 15s
call-ci / build (armv7m7-imxrt106x-evk)	1m 38s
call-ci / build (armv7m7-imxrt117x-evk)	1m 27s
call-ci / build (host-generic-pc)	1m 14s
call-ci / build (ia32-generic-pc)	1m 17s
call-ci / build (ia32-generic-qemu)	1m 25s
call-ci / build (riscv64-generic-qemu)	1m 8s
call-ci / build (riscv64-generic-spike)	1m 6s
call-ci / run tests on hardware (armv7m7-imxrt106x-evk)	4m 0s
call-ci / run tests on hardware (armv7m7-imxrt117x-evk)	2m 8s
call-ci / run tests on hardware (armv7a9-zynq7000-zedboard)	4m 5s
call-ci / run tests on hardware (armv7m4-stm32l4x6-nucleo)	8m 23s
call-ci / run tests on emulators (armv7a9-zynq7000-qemu)	5m 37s
call-ci / run tests on emulators (host-generic-pc)	1m 1s
call-ci / run tests on emulators (ia32-generic-qemu)	4m 16s
call-ci / notify ci team using e-mail	0s
	46m 12s

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