gaisler: refactor GRLIB APBUART driver #1443

Job	Run time
call-ci / build (armv7a7-imx6ull-evk)	1m 13s
call-ci / build (armv7a9-zynq7000-qemu)	1m 34s
call-ci / build (armv7a9-zynq7000-zedboard)	1m 9s
call-ci / build (armv7a9-zynq7000-zturn)	58s
call-ci / build (armv7m4-stm32l4x6-nucleo)	1m 15s
call-ci / build (armv7m7-imxrt105x-evk)	1m 13s
call-ci / build (armv7m7-imxrt106x-evk)	1m 15s
call-ci / build (armv7m7-imxrt117x-evk)	1m 16s
call-ci / build (host-generic-pc)	49s
call-ci / build (ia32-generic-pc)	1m 9s
call-ci / build (ia32-generic-qemu)	57s
call-ci / build (riscv64-generic-qemu)	56s
call-ci / build (riscv64-generic-spike)	53s
call-ci / build (sparcv8leon3-gr716-mini)	52s
call-ci / test HW (armv7a7-imx6ull-evk)	5m 55s
call-ci / test HW (armv7m7-imxrt106x-evk)	2m 37s
call-ci / test HW (armv7m7-imxrt117x-evk)	3m 27s
call-ci / test HW (armv7a9-zynq7000-zedboard)	8m 26s
call-ci / test HW (armv7m4-stm32l4x6-nucleo)	11m 24s
call-ci / test EMU (armv7a9-zynq7000-qemu)	8m 30s
call-ci / test EMU (host-generic-pc)	51s
call-ci / test EMU (ia32-generic-qemu)	6m 30s
call-ci / test EMU (riscv64-generic-qemu)	5m 29s
call-ci / tests-summary	14s
call-ci / send-notification	0s
	1h 8m 52s

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