remove iMX6UL dead code #1006

Job	Run time
call-ci / build (armv7a7-imx6ull-evk)	1m 37s
call-ci / build (armv7a9-zynq7000-qemu)	1m 52s
call-ci / build (armv7a9-zynq7000-zedboard)	1m 25s
call-ci / build (armv7a9-zynq7000-zturn)	1m 16s
call-ci / build (armv7m4-stm32l4x6-nucleo)	1m 24s
call-ci / build (armv7m7-imxrt106x-evk)	1m 39s
call-ci / build (armv7m7-imxrt117x-evk)	1m 54s
call-ci / build (host-generic-pc)	1m 7s
call-ci / build (ia32-generic-pc)	1m 15s
call-ci / build (ia32-generic-qemu)	1m 25s
call-ci / build (riscv64-generic-qemu)	1m 16s
call-ci / build (riscv64-generic-spike)	1m 7s
call-ci / run tests on hardware (armv7m7-imxrt106x-evk)	1m 48s
call-ci / run tests on hardware (armv7m7-imxrt117x-evk)	2m 7s
call-ci / run tests on hardware (armv7a9-zynq7000-zedboard)	4m 36s
call-ci / run tests on hardware (armv7m4-stm32l4x6-nucleo)	8m 23s
call-ci / run tests on emulators (armv7a9-zynq7000-qemu)	6m 23s
call-ci / run tests on emulators (host-generic-pc)	1m 12s
call-ci / run tests on emulators (ia32-generic-qemu)	3m 40s
call-ci / notify ci team using e-mail	0s
	45m 26s

Provide feedback